Most people are going to tell you a testpipe is best bang for buck, and gears.

 

Your best bet for your dollar will be gears. Change your final drive ratio to a 4.44, 4.56, or 4.77. Parts are not cheap for this car. Gears will run you around a grand plus or minus maybe less if you can remove the diff youself.

For me 4.44's $450.00 cryo treated the gears $65.00 installation was $170.00 diff fluid $10.00 total was about $700.00 my labor to drop the diff. This might not be bolt on HP but it sure does make the car accelerate much quicker and it is certainly more fun to drive. Since your an AP1 4.56 or 4.77 would be your best bet.

Swiftoy

 

Damn, congrats on your pickup. I bought a MY00 with 23k miles, and I thought that was amazing.

Like most people are saying, this car is hard to get more power out of without going FI, which is expensive. If you get a nice test pipe, and high quality single exhaust, I think you'll like the outcome.