I tried taller gearing BTW, which you can see in the 3rd picture laying on the table. Amazing how easily you can change the differential on these things. Anyway, I got the exact same top speed at a lower RPM and it took longer to get there. I'm gonna hold on to the rear gears and try it again at a later date if I do more mods that happen to cause more power. In the mean time I'd rather rev the motor up higher and have better acceleration.