The air filter that comes with the RYCA kit has a pretty small filter surface overall. Can anyone tell if its starving for air at all, or does it seem sufficient?

Somewhat along the same lines (because it takes up air filter space), why are we using the stock crappy battery for this build?  If we use a battery from a sportbike such as an R1 or CBR1000 the size of the battery is about 3/4 size of the stock battery for this bike.  I can say from first hand experience it starts the bike right up no problem.  Top brands will cost you around $120, but you can get a decent lower brand gel battery for only about $40.