I ran my 5700 on 66/12 gearing in an e-maxx. With MY OLD I.B. 3800's 6cell first then 10 cell it was ok, not real punchy, but not bad, but the batteries were getting warm. Then tried 4200's and wow the little motor would jump the truck clear over on it's top when it got traction, even taking off in 2cnd. 10 cells playing in back yard (short grass) would bring the motor up to 140-150F. This is on 40-50F days, often taking off in first and shifting quick. Speed was calculated for ruffly 41mph if the battery would recover to 11.66 volts before running out of room.