For a street bike u can go for a simple short geared setup. It would decrease your top end but would increase your acceleration. In simple words if u drag for quarter mile with other R15's u would smoke them easily. But for longer runs u cant and would lose out.
I feel its just another of those local races which people have on the streets risking everyone. Are u really interested in the getting some serious performance mods? No K&N. No Bullshit.
Are u ready to work on the engine internals? U would lose on engine reliability and of course the warranty.
U are seriously confused with what u need. A drag prep means the bike will have tremendous acceleration and performance and u cant use the bike for normal purpose Like going to a shop, going to college etc. A street prep is that in which the bike can perform pretty well (not as good as the drag bike) and can also be used for daily purposes.Now tell me what do u need. I can probably help u out with the things that have to be done.
NOS is a shortcut to make power, but will blow it by the time you realise. Wht is sold here is the dry NOS system and its not the best way to go fast at the cost of your internals and the engine reliability.
You can always make more power by doing a lot more stuffs.