I just bought a GTP and im looking for some performance ideas. Im willing to put about 3000-4000 into the car and want to get the most HP increase for my dollar. any ideas

Cold air intake, smaller super charger pully, headers, exhaust, PCM......

new supercharger....

I agree with WiCKeD. I've put about 1,500 into my exhaust, intake, and PCM on an 04 GT and I've increased my HP by about 50. And I don't even have headers. Make sure with your exhaust you get rid of the factory downpipe and put on an after market one with a high flow cat. I think 3" is the way to go, that's what I have on mine.

I have a stock cat, but the rest is SLP How you get 50? I also have CAI & exhaust, but I raced a 2002ish GTP and I was keeping up with my 04 GT1... I need a PCM

50 HP is just an approximate. I'd like to get it on a Dyno. But, add 15 HP or so for the K&N, a downpipe and high flow cat is around 15 HP, an upgraded exhaust from the resonator back is 10 HP to 15 HP. Then throw in the PCM. I also have upgraded plugs, wires, and ignition coils. My car moves pretty good!

You have to get rid of your stock converter. It makes a big difference!