Gsr Performance

i have recently got intake headers and exhaust for my gsr and i wanna take it a step Higher what would be a good step to take next?
that will give me a good amount of HP increase and doesnt cost too much?

N2O...best bang for the buck

If you dont want nitrous. Then i'd suggest you get upgraded cams. If you dont wanna spend too much then ctr cams is the best choice. IF you're willing to spend more then skunk2 stage 2 cams along with there upgrade valvetrain set up is a good way to go. You're lookin at 1500-1800 along with skunk2 cam gears for a complete set up.