what should i do first?????

i got a 99GTP w/83000 on her ... i need new pipes from the cat back. i want to get headers but not sure if needed?i wont mind get 300hp out of her but it will be a daly driver still. i want that 1.0 pcm/ 3.25 pulley/c.a.i but i dont know where to start:banghead::banghead::banghead::banghead:any ideas wood be great... im hoping for more hp/tq but dont want to lose to much MPGs.......................................PLEASE HELP:confused::confused::confused:

Exhaust and intake are good places to start for more power and better MPG. Do a u-bend delete, get rid of your cats if your state does not test for emissions or get high flow cats along with a full mandrel bent exhaust system. I am no expert on GTP's but I would guess a 2.75" exhaust would suffice for a boosted V6 of that proportion. Downsizing the pulley and raising your boost with supporting mods won't help out your mpg at all but also won't hurt it terribley if you can help staying under boost. Best of luck!

Mine too is starting to get a loud exhaust system.

Be carefull on certain header types, some have issues with leaks especially the cheaper ones. Do your homework.