Anti Lag	Blancing	Blow Off Valve	Boost Controller
Catalytic Converter	Clutch	Detonation	Drivetrain
Flywheel	Head Work	Intercooler	Manual Transmission
Rotors	Turbo	Turbo Timer	Water Injection

    When driving a car, and you change gears or back off a flap called the "butterfly" closes which stops the flow of air into the engine. In the case of a turbo powered car, the turbo continues to spin trying to compress air. Because the "butterfly" is shut, the air forces back on to itself, slowing down the turbo. When you start to accelerate again, the turbo has to spool up to re-develop boost. With a Blow Off Valve installed, it detects a vacuum on the engine side of the butterfly and opens the valve to dump excess pressure between the butterfly and the turbo. This reduces the restriction and allows the turbo to almost spin freely, which reduces the lag experienced between on and off acceleration.

    There are two main types of blow off valves: those that vent to the atmosphere (gives a large woosh sound when released) and those that recirculate the air back to the inlet filter. Some argue that you should not run a vented blow-off-valve on cars that use a air-flow meter because it confuses the airflow meter, causing the car to run rich or lean, which can cause the car to stall. I have experienced this with some poorly designed or incorrectly adjusted blow-off-valves when stopping suddenly, but it is not an issue if the device is designed properly.