Higher Kv motors are faster if the gearing stays the same, but that also increases amp draw, heat, etc. You can gear up a lower Kv motor so you don't necessarily have to have a high Kv motor. Larger motors mainly provide better torque and heat dissipation. The higher you push the speed, the...
Never ran it for top speed, but it's really fast for a parking lot bash. Made a kydex battery box to mount to the bottom of the chassis, that was the ONLY way to get the center of gravity low enough to do some serious street bashing. Got bored over winter and set it back up as an off road shelf...
I've run a Fast Lane Machine transmission case with a drag slash diff, same bearing size, just requires a couple of shims. The FLM case will work with 4068 motors or 4268 if you grind 3 or 4 of the fins down where it slides through to the motor plate which is what I did. Way easier keeping temps...