6200   S3 Tires
7200   Semi-Racing Suspension
13000   Supercharger
5250   Polish
11000   Balance
1250   Chip
10200   Full Race Trans.
4600   Race Brakes
4600   Race Exhaust
1100   Weight Reduction 1
5300   Weight Reduction 2
4250   1.5 Way Diff
1000   Racing Flywheel
50   Oil Change (cheesy 5% power boost)
75000   Total
I did the fastest lap with the default suspension settings.
I forgot to get the gear ratios, will post later.  I just used the little auto slider thing to adjust the whole set so it is about 500 rpm short of redline at the end of the "straight"
It's a pretty good car, has some understeer turning in, but you can neutralize it with trail braking and throttle.
It could use a brake controller and stiffer rear bar but no money left for that.  

Good choice GTO, it's a fun car.  Not a complete pig, and not a UFO even when modded heavily.  It even has a real life road racing pedigree.