I'll leave that one for the experts here. If my local track is any indication though...everyone I talked to when I stopped by today was running a 4.5T. Of course for all I know the owner may have talked them all into the same motor! Love the username by the way. That's exactly where mine comes from. The Armies of the Southern Cross. I'll have to show you my pics of my Robotech collection one day. I've had that handle since back in the BBS days.

Almost forgot about my pinion. I have case full with a nice selection of pitches buried somewhere. I'll do some trial and error. I usually run on the safe side...picking longevity over speed...course I'm not a racer.