what's the difference between 4600/5700/7700 motors?
I believe those numbers refer to the unloaded RPM per Volt. Not sure on Mamba's though. (Novak 5800 and 4300 that is what those numbers refer to, but for the 3.5,4.5,5.5, etc you have to refer to the Novak site, but the 3.5 = 10,500 rpm per volt unloaded)
As for the MAMBA 7700, WOW it's fast. Nic Case ran his w/ 4 cell at our VELODROME oval race last weekend. 264 meter track in 8.7 seconds w/ 4 cells...of course that's in a PAN CAR. The NOVAK 3.5 were fast too, turning times in the 9.0 range.