I ride a blue and silver 07 and this was the order of my mods. This may not be the best for you if are new to the sport on the other hand these mods have dramitically improved the performance and of my bike.
-sliders
-swingarm spools
-corbin seat
-dub bub zero gravity windscreen
-520 chain conversion -1+2
-speedo healer
-power commander
-bmc racing airfilter
-Akropovic full race exhaust
Next is dyno tuning and supension work but that will have to wait till next season.
The akropovic exhaust is not cheap but it is probably one of the best overall systems out there. If you don't do the a lot of freeway riding the 520 kit is awesome for everyday fun and is not that bad on the highway. I have done these mods in a 8 week period and have been able to enjoy every step up in performance. The power commander even with stock exhaust and airfilter made the bike run much smoother and crisper.