Muffler:

Sports
"Combines a less-restrictive replacement sports-model air cleaner with a low back-pressure sports muffler to improve intake and exhaust flow. Ideal as a first-time turbo upgrade. Improves high-rpm torque in non supercharged engines."

Semi-Racing
"A competition-grade air cleaner with urethane sponge filter is combined with a low-back pressure muffler designed to enhance engine performance at high rpm. Ideal for large-displacement turbo engines. When using with a non-supercharged engine, proper tuning beforehand is a must."

Racing
"Delivering even better intake efficiency than the semi-racing model, this racing air cleaner with a velocity stack is combined with a high- efficiency straight muffler designed for racing cars that normally operate in the high-rpm range. Suitable for tunings that maximize peak power. Reduces low-rpm torque and so requires proper consideration of engine characteristics, gear ratio, and other factors."

The long and the short of it is that the muffler upgrades kick up your horsepower. They're no substitute for actual displacement, but they can give you a very useful boost, especially early in the game -- this is a good cheap upgrade to consider when you're starting out.

NA Tune-up:

Stage 1
"Boosts the power of non-supercharged engines by adjusting the ignition and valve timing and by installing thinner head gaskets for a higher compression ratio. The exhaust manifold is also replaced. Peak power is enhanced without affecting low-rpm torque."

Stage 2
"Picks up where Stage 1 leaves off. Not only raises the compression ratio even further with high-compression pistons and head polishing, but also boots high- rpm output by replacing the cams, mounting reinforced valve springs, and Port and Polish. Although low-speed torque is diminished somewhat, the emphasis here is on boosting high-rpm power. The Engine Management Computer is also reset according to your vehicle specs."

Stage 3
"Following up on Stage 2 enhancements, this upgrade completely overhauls the engine to enhance high-rpm performance. Higher-compression pistons, special high-lift racing cams with a large amount of valve overlap, heavy-duty competition valve springs and connection rods, and engine block strengthening are all part of the package. The power band is shifted to the medium to high range to boost maximum horsepower."

"NA" stands for Normally Aspirated. It refers to an engine that doesn't have assistance in forcing more air into its cylinders -- i.e., it doesn't have a turbocharger or a supercharger. In GT3, NA Tuning works somewhat like turbocharging, giving you a remarkable increase in power, but the effect is somewhat different in practice. You don't have the striking effect of turbo lag that pops up in highly-tuned turbo engines.

GT3 differs from its predecessors by very frequently offering the option to upgrade a car with either NA Tuning or a turbocharger. In GT and GT2, it was generally impossible to add a turbo to an NA car, but now you can, and so you should choose according to which option gives you the best power for the circumstances and suits your tastes in driving. It's also worth noting that, for finesse drivers, the most power is not necessarily the best thing. A massive power upgrade looks like fun on paper, and it may win you races, but you'll also have a more pronounced tendency to whim-wham off the walls on your way to the finish line if you sack your low-rev power -- it hurts your cornering ability, especially if you don't have the tires and suspension modifications to keep that power under control. Choose wisely, then.

Port Polish
"Polishes the interior of the intake ports, reducing air-flow resistance boosts engine power by what may seem a low degree, but is essential for normally aspirated and supercharged engines alike."

Not a lot of horsepower here, but like they say, an important accompaniment for a highly-tuned car.

Full-Engine Balancing
"An extensive upgrade that includes piston and connecting rod weight balancing, and a precision-balanced crankshaft. Reduces vibration and bearing loads, and allows higher engine speeds. The rev limiter is reset to take advantage of this."

This is another one of the minor horsepower upgrades, but a useful one for more ridiculously powerful cars.

Displacement Up
"There's no replacement for displacement. This upgrade raises cylinder displacement by increasing engine bore and stroke. Greater displacement generally boosts the engine's torque in all rpm ranges."

This modification kicks up your engine's power at the most fundamental level, increasing the bore and stroke with bigger cylinders and other parts. Many cars don't have access to this upgrade, it mainly being reserved for pushrod engines like the one in the Viper, but take it if you can.

Racing Chip
"The most basic upgrade. Altering the Engine Management Program settings allows you to boost power by adjusting engine ignition timing, the air/fuel ratio, and other variables. For turbocharged vehicles, the air filter and muffler are also replaced, for a beginner's-level upgrade."

What he said. A cheap and cheerful horsepower upgrade, very good for adding a little extra kick to your first car.

SUSPENSION & BRAKES

Suspension:

Sports
"An all-purpose, beginner-friendly suspension kit that covers all types of driving, from street to circuit. Both front and rear shock absorbers are adjustable to one of 10 damping force levels. Camber angle is also adjustable. Clearance is lowered approximately 1 inch in the front and back. Two-way low-pressure gas shock absorbers (adjustable to 10 levels)."

Semi-Racing
"A ride height-altering suspension kit for intermediate drivers. Spring rate and the shock absorber damping force are harder than with normal sports suspension. Front and rear ride height is adjustable in 1-millimeter increments. Damping force is adjustable to one of 10 levels, and camber angle is also adjustable. Single high-pressure gas shock absorbers."

Full Customization
"Enables tuning of all suspension parts. Adjusts shock absorbers, replaces springs with ones with different spring rates, and replaces the stabilizer (anti-roll bar), which controls the vehicle's lateral roll stiffness. Wheel camber can be changed, and toe-in is also adjustable. Shock absorber compression (bound) and extension (rebound) are independently adjustable to one of 10 levels."

Suspension modification kits do a little on their own to alter and improve your car's handling (for example, the Sports kit lowers your ride height for a lower center of gravity and better handling), but their real purpose is to enable you to make changes -- hopefully for the better -- on your own. The Sports package unlocks a few tuning options to a limited degree. Semi-Racing increases the amount of latitude in those areas and adds the ability to tweak your car's ride height at will. Full Custom unlocks the broadest spectrum of suspension setting options, allowing you to tune a racer for peak performance. For advice on what to change and what to leave alone, see the Settings Guide later in this section.

Racing Brakes
"Contains carbon metallic brake pads for dependable stopping power, even during long-distance driving. With far more initial stopping power and fade resistance than ordinary brakes, these brakes are also suitable for endurance races. Brake fluid (DOT 5) is also changed."

What you see is what you get. Racing brakes give you better stopping power, and if the game simulated brake pad wear like it does tire wear, they'd probably last longer, too. They're a vital complement to serious power upgrades.

Brake Balance Controller
"Controls the anti-lock braking system to maintain the desired balance in braking power between the front and rear brakes. Strengthen the front to increase understeer for extra stability, or strengthen the rear to increase oversteer for better maneuverability. Remember that a too-strong rear brake balance increases the likelihood of spinout."

In practical terms, what this does is unlock the brake balance options in the Settings menu. If you want to fiddle with your front and rear brakes, you'll have to fork out the coin for this upgrade.

DRIVETRAIN

Clutch:

Big Single Plate
"Changes the clutch feeling during upshifting, so that upshifting feels more direct than with a normal clutch. Also improves speed of shift a little."

Double Plate
"This racing clutch kit features dual clutch places, ideal for high-torque, high- power vehicles. Reduces clutch slippage during upshifting, improving acceleration due to less time spent between shifts."

Triple Plate
"Featuring three clutch places, this clutch kit boosts torque transmission and enhances the directness of the power. Ideal for highly-tuned cars. Fastest upshifts."

The clutch is the weak link when it comes to fast shifting -- gear selection means nothing if the cogs don't engage and disengage smartly. The three clutch upgrades respectively kick up your shift speed a little bit more, with the triple-plate clutch being the one you want for a high-powered car that needs to get out of the corners and into its high-rev powerband quickly.

Flywheel:

Sports
"A lightweight flywheel made with chrome molybdenum steel. Lets the engine rev more quickly. Improves acceleration slightly, but with narrow-powerband engines, revs may drop below the powerband unless a close-ratio transmission is also used."

Semi-Racing
"Even lighter than the sports type, this flywheel is especially designed for racing. Makes for a quick-revving engine. Improves acceleration slightly, but with narrow-powerband engines, revs may drop below the powerband even more easily unless a close-ratio transmission is also used."

Racing
"A super-lightweight flywheel exclusively for racing. Makes for a quick-revving engine that also drops revs quickly. Improves acceleration and deceleration, but with narrow-powerband engines, revs may drop below the powerband unless a close- ratio transmission is also used and the driver can master the proper shifting technique."

The flywheel modifications play a role mainly when you're using the standard transmission, since the game's version of an automatic transmission will naturally take care of that proper shifting technique for you. If you shift for yourself, you'll have to work with this particular modification to get the most out of it, and possibly do a little gear ratio tuning to keep your acceleration smooth.

Carbon drive Shafts
"A lightweight driveshaft made with a carbon composite. Situated between the engine and the differential gear in front-engined, rear wheel drive or all wheel drive cars. Not available for Front Wheel Drive cars. The driveshaft is just as important as the flywheel for acceleration performance."

This simple modification isn't available for some cars, but when you can buy it, it's a good choice to reduce your weight and kick up acceleration.

Transmission:

Sports
"Replaces a normal transmission assembly with a transmission with closer gear ratios in all five gears. Prevents revs from dropping below the powerband when upshifting, and allows smoother downshifts. Ensures useful power in a variety of turns. Recommended for non-supercharged engines."

Semi-Racing
"These gear ratios are even closer than those of the Sports Close- Ratio Transmission. This gearbox is ideal for highly-tuned cars with a narrow powerband. Note that upshifting and downshifting will become more frequent. Because of time loss during shifting, this transmission may be counterproductive in cars with high-torque, wide-powerband engines."

Full Customization
"For races that permit the replacement of all gears, including the final drive gear. This upgrade also makes it possible to fine-tune the gear ratios according to vehicle specs and circuit features."

Respectively, then: Sports is good for a lower-power street-type car. Semi-Racing is what you want in something comparatively serious, and Full Custom is the choice for the serious racer. Full Custom's advantage is that it unlocks the complete selection of gear ratio options in the Settings menu, so if you want to fool around with your ratios (and you will, if you get deep into the game), you need the most expensive transmission package. See the settings guide for advice.

Limited-Slip Differential

1-way
"This limited-slip activates the limited-slip effect only during acceleration, and so is suitable for front wheel drive vehicles, which are difficult to turn under any conditions. The absence of the limited-slip effect during braking makes it possible to maximize turning power. However, the tendency of the vehicle to lose stability during braking should be noted. The shortcoming of this type of limited-slip is that vehicle characteristics during acceleration change greatly when the accelerator is released to decelerate."

1.5-way
"Reduces the limited-slip effect during deceleration while maintaining the full limited-slip effect during acceleration. This ensures powerful traction, and during braking, prevents excessive reduction in the force of the car attempting to turn. Free of quirkiness, this is a good all-around limited-slip unit."

2-way
"A limited-slip differential that delivers the limited slip effect during both acceleration and deceleration. Stabilizes the vehicle attitude during braking, thereby permitting even harder braking. Delivers powerful traction during acceleration, but clearly makes turning more difficult and so is suited to drivers who are skilled at turning."

Full Customization
"This special racing modification allows independent adjustment of the limited-slip effect during acceleration and deceleration. Although capable of greatly changing a car's performance, this modification requires careful adjustment as improper adjustment can destroy the car's balance."

The differential is the set of gears on your car that marries the driveshaft to the drive axle. A limited-slip differential, occasionally described as "positraction" (as in "four-speed dual-quad positraction 409," for you Beach Boys fans), is a widget that controls the torque split between the drive wheels, sending more torque to one wheel so as to give it more power. For practical driving, this is handy for keeping both wheels moving your car, even on slippery surfaces -- the wheel that needs more power to grip gets it. For racing, it also has its uses, maintaining uniform grip so you can get braking and acceleration force down to the track when you're heading into and out of a turn.

As for which one you want to buy, total gearheads should naturally take the Full Custom option, since it unlocks the broadest selection of variable LSD settings. 1-way and 1.5-way both work quite well for FF cars, and the 1.5-way offers the most effect for beginning drivers who don't quite have a handle on when to brake and when to accelerate in a turn. If you think you really know how to apex, though, you'll get the most out of the 2-way.

Be warned, however, that it's possible to throw your car completely out of whack by fiddling with the LSD. See the settings section for some tips.

TURBO KIT SYSTEM

Turbo Kit:

Stage 1
"A turbo kit that uses a compact turbocharger to generate high-rpm torque without sacrificing torque in the low to medium rance. Minimal turbo lag and high response combine to create an excellent balance suitable for all types of circuits. metal gaskets, oil coolor, a reinforced oil pump, and other high-durability parts are also installed."

Stage 2
"A turbo kit that stresses high-rpm peak power and low to mid-range balance. Torque in the low range is somewhat low compared to Turbo Kit 1, but mid to high range power is boosted considerably. In addition to metal gaskets, oil cooler, a reinforced oil pump, and other high- durability parts, a fuel pump, injector, computer, and other turbo components are also installed."

Stage 3
"A turbo kit that focuses on quarter-mile acceleration. The powerband shifts further into the high-rpm range than with Turbo it 2. For greater effectiveness, this turbo kit should be combined with a close-ratio transmission and other parts. The cam is also replaced with one designed for turbo characteristics. In addition to metal gaskets, oil cooler, a reinforced oil pump, and other high-durability parts, a fuel pump, injector, computer, and other turbo components are also installed."

Stage 4
"An oversized, high-rpm, high-output turbo kit designed purely with maximum horsepower in mind. Suitable for maximum-speed contests, for instance. The cam is also replaced with one designed for turbo characteristics. Ina ddition to metal gaskets, oil cooler, a reinforced oil pump, and other high-durability parts, a special fuel pump, injector, computer, and other turbo components are also installed."

A turbocharger derives its name from its mechanical centerpiece, a turbine. That turbine spins at an extremely high rate to power a compressor that forces more air into the intakes, improving the power and efficiency of combustion. Just for trivia's sake, though GT3 draws no practical distinction between the two, a supercharger does the same thing, but also steals a little mechanical assistance from the engine's driveshaft (for a nice visual lesson in how it works, watch the opening chase in The Road Warrior).

The turbocharger is likely the most popular upgrade in any GT game, and it's definitely one of the most effective when it comes to boosting your performance. It's worth noting, however, that it's not necessarily worth the cost or the effort to turn your ride into a drag racer just for the sake of posting the highest possible horsepower number. Remember that RUF set its speed record in a car with less than 500bhp. That monstrous horsepower is balanced somewhat by turbo lag and loss of torque in the low revs, which makes it tough to climb out of low speeds in case you spin out or crash. In very imprecise terms, you sacrifice some acceleration for that evil top end.

Thus, when you equip your turbo, it's wise to also have the corresponding parts for better acceleration (like the flywheel, clutch, and prop shaft modifications) and transmission modification. A Full Custom transmission lets you tune your ratios to compensate for problems at the low end and stretch out your potential at the top end.

Intercooler:

Sports
"This air-cooled intercooler cools the hot intake air after it is pressurized by the turbocharger. By lowering the intake air temperature, air density is increased, allowing for more fuel to be used and boosting power. An essential part for a high-performance turbo engine."

Racing
"Boosts the power of a supercharged engine by lowering the intake air temperature. The larger capacity increases the temperature-reducing capabilities but slightly lowers engine response. This high-capacity intercooler is a suitable upgrade for engines with a high maximum supercharging pressure."

Practically speaking, an intercooler just provides a horsepower upgrade to complement that provided by a turbocharger, but there's no reason to turn down extra power at this price.

TIRES

Sports
"Sports tires are for paved-road driving and have a greater grip than normal tires. Mounting high-performance tires enhances a car's cornering, acceleration, and braking performance and is the most effective upgrade. Purchasing tires entitles you to subsequent tire services for as long as you own those tires. Front and rear tires must be purchased together."

Sports tires are cheaper than racing slicks and demand a little less pondering of the balance between hardness and grip. Kit out a street racer with these and you'll see a nice improvement in all areas of handling.

Racing

Racing tires, also known as "racing slicks," are nearly treadless tires used exclusively for high-speed driving on the glass-smooth surface of a racetrack. In GT3, there are six types of racing tires:

Super Hard
Hard
Medium Hard
Medium
Medium Soft
Soft
Super Soft

The harder a tire is, the more resilient it is, the longer it takes to warm up to maximum efficiency (when you see race drivers doing zig-zags during caution laps, they're warming their tires), and the less grip it offers. In GT and GT2, there was essentially only one choice: Super Soft tires provided the most grip and needed no warming, so they were the best option, despite their high price. GT3, however, throws a bigger kink into the tire situation, because tire wear is a factor in many more races, and tires generally wear out much, much faster than they did in the previous games. A set of Super Soft tires will now die before the end of a five-lap race, although you'll corner on rails for as long as they last.

Thus, go ahead and run Super Soft tires in races with no tire wear, but you'll want to turn to a compound on the harder side of the spectrum for the tire-wear-enabled races in the Amateur and Professional leagues. Try out various compounds once you have some money to play with and see which one offers you the best balance -- we like Hard or Super Hard for endurance races, but that may be a bit on the conservative side.

Professional
"A tire that even more closely approximates the characteristic of actual, real-life tires. These tires make driving with the game controller extremely difficult and so provide a virtual experience of real-life driving (as opposed to video-game driving), requiring early braking, careful steering, and delicate accelerator manipulation. This is a set of front and rear tires for paved surfaces."

If anybody actually uses these, we'd like to hear their comments. So far as we can tell, they're only for the curious or the demented.

Rally
"Dirt racing tires, which must be mounted on all 4 wheels for racing on dirt courses. These tires are designed to ensure vehicle controllability on slippery gravel and other unpaved surfaces. Dirt racing tires are available only for certain vehicle types."

Rally tires are essentially just a racing license for the rally championships. It's surprising how many cars in GT3 can run them -- it's not just Lancers and Imprezas. Bolt some knobby tires on your turbocharged Skyline and you'll run away with most special stages.

STABILITY CONTROL & OTHERS

Weight Reduction:

Stage 1
"Lightens the vehicle by removing unnecessary parts and replacing others with parts made of lightweight-material. The numerous advantages of a lighter car include enhanced acceleration performance, improved cornering and braking, and better tire durability."

Stage 2
"Lightens the vehicle more by removing more parts and/or replacing more with lighter materials."

Stage 3
"Takes Stage 2 lightening a step further."

Power is only half of what makes a car go fast. The real key is power-to-weight ratio, the comparison between the amount of power delivered by the engine and the amount of steel/aluminum/ceramic/carbon fiber that power has to push forward. A Dodge Caravan has more horsepower than a Lotus Elise by some distance, but it's not going to beat one off the line any time soon. Weight Reduction, then, is vital to building a fast car, and it's one of the upgrades you want to buy early on, especially considering how cheap the first two stages are.

AYC Controller
"This component changes the setting of the Yaw Control System, which generates rotational moment in the vehicle by controlling the distribution of torque between the left and ride drive wheels. Raising the setting creates rotational moment during cornering, for better acceleration during turns. Note that too high a setting increases oversteer, and thus the likelihood of tire spinning."

In real life, there are several different specimens of what's generally referred to as Active Yaw Control. For the most part, though, they work somewhat like the limited-slip differential, automatically varying the torque split between either side of the vehicle to shove it in one direction or the other. In theory, you want the AYC to help push you into a corner just enough -- that's how it works in most road-legal cars, forcing them to follow a safe and sane cornering line in spite of potentially dangerous acceleration on the driver's part. In GT3, though, it can do a variety of things depending on how you set it up. Check the settings section for advice.

VCD Controller
"This center differential makes it possible to change the front and rear torque distribution in a 4WD vehicle. The setting range is 100% front/0% rear to 0% front/rear 100%. A 4WD vehicle can be made to handle like an FF car by shifting the torque distribution to the front wheels or like an FR car by shifting the torque toward the rear wheels. Torque distribution cannot be changed while the vehicle is moving."

This is an all-new modification for GT3, but you can only apply it to certain 4WD cars. If you remember from our discussion of differentials earlier on, the diff is what joins the driveshaft to the axles. FWD and RWD cars only have one, since there's only one axle talking to the road. A 4WD car, however, has three: one in front, one in back, and one in the center. The VCD controller lets you mess with the torque split that happens in that center differential, sending more or less power to the front or rear. How you set this is essentially a matter of taste, but if your driving style leans toward one end or the other, this could give you an advantage on the special stages in an Impreza or Lancer, or on the GT circuit in your Skyline.

SETTINGS GUIDE

Before you go to the racetrack, you have the option of altering many of your car's settings, and the more tuning parts you buy, the more settings you can tweak. This is the province of advanced GT3 drivers, who want to get the absolute peak performance out of their cars -- less committed racers can still walk away with a win using the game's default settings.

The following is a brief guide to what you can change and what effects those changes will have. Incorrectly altering many of these settings can completely destroy the performance of your car, so the most important advice regarding settings changes is to use caution. Before you start tinkering with settings like suspension, gear ratios, LSD, and stability control, save the default setting to a memory card, or just get a sheet of paper and write down the original numbers. You don't want to find yourself with a completely out-of-whack car that you can't retune back to normal behavior.

SUSPENSION

SPRING RATIO
Adjust the hardness of the springs.
The stiffer you make the springs, the faster and more responsively the car steers. However, over-stiffening the springs makes the car very unstable on rough roads. Some courses have smoother roads than others -- the smoother the road, the stiffer you can make the springs. Thus, stiff springs are a poor choice for rally courses, or something like Laguna Seca, but they may give you an advantage on a gentler course like Special Stage R5.

RIDE HEIGHT RATIO
Adjust the height of the car.
Lowering the car's height lowers its center of gravity and makes it more stable on the road. However, over-lowering the car causes it to bottom out, which means you can completely go out of control following a jump or particularly vicious bump. This can be balanced by increasing the spring ratio and damper ratio -- but race the track continually while adjusting to ensure maximum balance for each particular track. Again, the smoother the track, the lower you can adjust the car.

SHOCK ABSORBERS
Adjust the decreasing strength (dampening ratio) of the damper.
The softer the dampers, the more the car rolls into corners and over-reacts to bumps in the road. The harder they are, the more unstable the car gets out of corners. Some of the lighter cars have problems getting their power down cleanly on the road -- their tires spin and the car shakes. By softening the dampers, the tires are able to grip better -- the down-side is that the body roll is over-exaggerated through corners. When this happens, adjust the Spring Ratio and to lessen the effect.

CAMBER ANGLE
Adjust the negative camber angle. Camber angle is the angle at which your tires sit in relation to the car when viewed from the front or rear. This makes little difference to overall performance, and setting this wrongly can completely ruin the car's handling, braking and steering. A slight tweak negatively (so that the tires lean slightly towards the car) increases the car's stability through corners, but this is offset by loss of braking ability and steering effectiveness. In most cases, it's best to leave this as is.

TOE ANGLE
Adjust the toe-in or -out of your tires.
Toe angle is the angle at which your tires sit in relation to the car when viewed from the top. Like camber, a little negative toe can improve handling, but it's not a major factor in performance, and too much toe either way can seriously damage performance. It can also increase the speed of tire wear, which is a much bigger factor in GT3 than it was in GT2.

STABILIZER
Adjust the roll rigidity of the stabilizers.
The stabilizers affect the car's cornering ability by making it more stable. Over-adjusting the stabilizers causes the car to become over-reactive on the straights. Under-adjusting makes it roll through corners and become very unstable. Just remember -- the car's stability is also directly affected by the dampers and spring ratio -- so adjust this in relation to the other two.

BRAKE
Adjust the brake balance front and back.
The more powerful the brake setting, the more the car's weight is thrown forward during the braking process. This can cause real handling problems if you brake while turning. Basically, the more powerful the front brakes, the more the car understeers (that means it wants to carry on in a straight line) and the more powerful the back brakes, the more the car oversteers (the back wants to slide around). The latter condition is more preferable because it helps the cornering effort, but can cause a loss of traction. Tweak the brakes to suit your driving style, starting with the rear brakes first.

DRIVETRAIN

GEAR RATIOS
Adjust the ratio for each speed gear.
Left lowers, right raises. Lowering the final drive ratio reduces the car's acceleration, but enables it to reach faster speeds (idea for a top speed test, for example, or very high speed courses). The higher the final drive, the better the acceleration, but it lowers top speed. Adjusting each individual gear ratio enables you to ensure that the engine revs are always kept in the car's power band. This is particularly important for turbo cars where the power band kicks in at higher revs -- by not keeping the revs in the power band results in very poor pickup, reducing the car's low- and mid-range performance, drastically affecting the car's performance on the more twisty tracks.

GT3 has brought back the handy-dandy gear graphs from the original GT, so it's pretty easy to intuit what kind of results your individual gear changes will have. The farther forward on the graph the gear's little line goes, the more top speed you'll get. The steeper the line is, the faster you'll accelerate through that gear. This being a game, you can do stuff with your ratios that would turn your transmission and engine into hash in reality. For example, you might want to have very short low gears and very long high gears. The vast majority of shade-tree tuners, though, will want to just use the "Short-Long" slider at the bottom of the menu to quickly trade off between acceleration and top end.

LSD -- INITIAL TORQUE
Adjust the initial torque provided by the LSD.
Depending on your car's drivetrain, you'll have one or two options here. FF cars can change the front setting, FR cars can change the rear, 4WD cars can change both. Raising the initial torque increases your stability in turns, but at a cost in cornering ability -- i.e., it's harder to turn. Generally, raising the initial torque is not recommended, except for Drift Kings with a knack for using the accelerator to push themselves around turns.

LSD -- ACCELERATION
Adjust the effect of the LSD while accelerating.
A higher LSD acceleration setting gives you more grip when accelerating, for faster acceleration out of a corner, but a corresponding decrease in grip when decelerating, which can cause a loss of stability while braking. This can be moderated by adjusting the LSD deceleration setting as well.

LSD -- DECELERATION
Adjust the effect of the LSD while braking.
Take the LSD acceleration description and turn it around. A higher LSD deceleration setting gives you more grip when braking, which makes for more comfortable turning when you slow down quickly, but less when accelerating, which you can compensate for by adjusting the LSD acceleration setting.

MISCELLANEOUS

DOWNFORCE
Adjust the downforce.
Increasing the overall downforce (by adjusting both front and rear by the same amount) essentially makes the car heavier, this making it more stable at higher speeds. However, this increase in "weight" is to the detriment of top-end performance. If you follow auto racing at all, you'll hear plenty of discussion about drag as it relates to spoiler angles, and this is at the heart of that -- downforce is good for handling and stability but bad for top speed.

Meanwhile, changing front or rear downforce individually can affect cornering. Increasing the front downforce alone causes it to oversteer. Increasing the rear downforce causes it to understeer. Thus, more rear downforce can give you a cornering advantage in a tail-happy car, while more front downforce will push you into a turn more effectively if your car would rather stay in a straight line. [Reverend's note: Thanks to those who wrote in to correct this bit in the first rev of the guide.]

AYC CONTROLLER
Adjust the setting of the Active Yaw Control.
The AYC slider determines the effect that a car's Active Yaw Control system has on its performance in turns. A higher setting will assist in pushing your car through the turns, enabling better acceleration in the corners, but if it's turned up too high, the possibility of fishtailing and spinning out becomes significantly greater. Not that many cars have AYC, so you probably won't find yourself adjusting this very often anyway, but as with all professional-level modifications, use caution and remember the initial settings so you can reset them if your performance is seriously degraded.

ACTIVE STABILITY MANAGEMENT(ASM)
Adjust the setting of the ASM controller.
Some cars have ASM, some don't. This is a system that automatically controls the brake force distribution to all four wheels. In practical applications, it's used to slow the vehicle during cornering and give it strong yaw moment when it gets out of hand in the corners. In GT3, you can set it high to provide more grip in corners, but this comes at a cost in acceleration and handling response. Set it low and you lose some of that stability, but you gain back the responsive steering.

TCS CONTROLLER
Adjust the setting of the Traction Control System.
Traction Control is a catch-all term for a variety of systems that limit power to a wheel that is losing grip on the road. Some use a limited-slip differential, some use automatic braking, some use automatic control of the drivetrain. In all cases, their effect is to increase stability and grip in the corners, albeit at a loss in speed when going flat-out in the straights. The TCS can be a boon to cars that are difficult to handle in the corners, though, so this is an option worth exploring.

VARIABLE CENTER DIFF CONTROLLER(VCD)
Adjust the setting of the VCD system.
As mentioned above, the Variable Center Differential lets you control the torque split between the front and rear wheels of a 4WD car, making its behavior more like a front- or rear-wheel-drive car. Put it all one way and you have an FF car; all the other and you have an FR car. Adjust it to suit your driving style if you have a 4WD car you particularly want to tinker with, but as always, remember what to set it back to if things go awry.