Let me get this straight...
You have:
Pulleys
throttle body - (No gain on a near stock setup)
3.73s
Intake - (You mean a Cold Air Kit right?)
Exhaust - (H\X-pipe or just a cat-back system?)
Is this a vert? Well driven '00 GT coupes should be running mid-low 14s bone stock, so 13s aren't that tall of an order...
Get yourself a Pro-M or C&L MAF... that should help a bit.
If your exhaust is just a cat-back system, its time to go with an H\X-pipe, that will give you a few horses too...
Best investment?
Get some drag radials and some hard core experience at the track... What are your 60 foot times?
Then start saving money for a blower...
