Hell if you got the power try a 16t... the taller the gearing the easier it is to ride a 'shee around a track..... I think a 17 would be too much... 16/39 is as far as I would take it... With my -2.5 swingarm, 15/41 gears, pipes/reeds/165psi I could drop it in 2nd with the front tires lofting about 6''.... People don't know what to think when a 'shee grabs traction...
Mike