<3 my nerf guns :]
I just turned my Raider CS-35 (blue one, top right) from a pussy into a beast. All I had to do was remove the air restrictor. Didn't need to go further than that.
Though I probably will at some point ;D
Oh, and note the Nerf Nitefinder at the bottom. I removed the air restrictor from that one, replaced the spring, and added a bit more power with a really thick elastic band. It shoots the furthest of all my nerf guns :]