Higher kv vs. taller gearing

[BrianG]

Personally, 35-40k rpm is on the high side for feigaos. Of course, that depends on how long you stay at top speed. I usually shoot for 35k as the top end of the rpm range, but tend to like the 30k-32k range. Any loss in speed can be regained with gearing within reason.

4s is good for 30-35mph without large currents, but that depends on vehicle size/weight, drivetrain drag, etc. Gotta remember it takes power to move your truck, and power is Volts x Amps. If it takes, say, 1500w to achieve the top speed you want with the acceleration you want, it will take less current to get that power at higher voltage.