+1
The whole induction system is a bottle neck from the airbox to the intake valve. Cams will yield very little for what you're going to spend putting a set in (cams, springs, retainers, adjustable gears, etc). I wouldn't consider changing cams without re-working the head, but you're going to spend substantially more money for very little gain.
If you want the biggest bang/buck, go with the best exhaust you can afford (Akrapovic or TiForce), and nitrous. Sounds like you're mostly drag racing anyway with the extended arm.
For my riding, NA works best as there's no turbo lag, and I don't need nitrous. I just like a big motor that pulls hard when you want it to.