Ok I have a 03 GT with 5 spd. I have bbk lt headers, bbk or h pipe, flowmaster catback, k&n filter, pulleys, diablo delta chip, and 3.90 gears. My question is this. Would I benefit from porting out my stock PI heads or would I be better off just buying a set of heads. what would i pay to get it done and what kind of power could i expect from doing it.