Best Performance Increase

[Gary Drexler]

What would the best bang for the buck to increase the performance of an 04' GTO,
without compromising the integrity of the engine, or exhuast?

1) nitrous oxide kit (how much $$ to refill the bottles)
2) heads / cams pro performance package
3) cut out mufflers only and replace with straight pipes
4) reprogram factory computer settings with an SLP Predator