look at the stickies at the top of the fouth gen section click the one that says where to start modding. then check the prices for the mods. headers, exhaust, cai and tune and most of the money is gone. check my build thread. im pushin somewhere close to 400
Not going to get 400 at the wheels for very long if you are only planing to spend 2500 total. At 400rwhp your over 450 at the crank and your stock 4L60 is not going to be very happy. You have a decent budget and can really wake a LT1 up with that. Defiantly invest in a good converter along with any power mods.
CHEAP, FAST, RELIABLE YOU CAN ONLY PICK TWO
2000 WS6 TTI T76 turbo,, RPM stage 5 4L60, Mosor 12 bolt, 524 rwhp/499tq
2001 WS6 409ci LQ9 Iron Block. 11.3 compression. 243/251 cam, 9 inch, T56,