So far the truck has the Intense Performance Stage II air intake system and a Fastman modified throttle body. The resulting increases in horsepower, fuel mileage, and overall performance more than made up for the expense.  As other systems wear out in the normal wear and tear of a vehicle, they will be replaced with upgraded aftermarket systems, such as a Flowmaster high flow muffler, MSD ignition wires, etc.

I switched over to Mobil 1 synthetic oil in the motor at 3K and Redline fluids in the diffs and tranny at 12K.
Intense Performance
Stage II Air Intake
Tired of not having light right in front of the truck when you flip to high beams?

This mod shows the jumper required to have your fog lamps illuminated along with the high beams. Simply pull the fog lamp relay out and put in a jumper across the 2 sockets that are perpendicular to the 3 sockets. Leave the remaining 3 sockets empty and save the relay for a spare.
Performance Mods
Fog Lamp Relay Jumper
TB - Before and After
Fastman modified Throttle Body
More Mods
This is the Fastman modified throttle body. The resulting HP gain, throttle response, and overall performance is well worth it.
Check out "The Fastman" at:
http://www.thefastman.com/thefastman/
Here is the Intense Performance Stage II air intake system with a 9" Big Mouth filter. This mod increased both horsepower and mileage. 

Check out air intakes and filter systems for your rig at:
http://www.intenseperformance.com
The only mods we have done have been to the 2000 Flame Red Beauty. Planned mods for Sandys 2003 Graphite D include a Fastman TB in the near future. I'll also be changing over to Mobil 1 in the motor and Redline in the tranny and diffs.