the 3.8 is really slow w/o boost.
it seems tehh fastere the motor, the bigger difference between boosted/unboosted speeds. either way, nothing is considered fast without boost. .
2.6 is one of my faves for the boosted, as well as the zz nos, mainly due to the difference in boost and no boost is close enough to be usable on a track.
I would make a chart, but i don't have enough resources and time right now to do them all, plus my booster got stepped on the other day, and i have to do another pcb transfer

(first one was when doing my zz pcb xfer, I accidentally used my reference car's pcb whhich was wrong frequency.....DOH!)