Originally Posted by
klaymon
If your ESC has a setting called Throttle PWM (Pulse Width Modulation), that can affect top end, but to what extent I can't say. Higher PWM settings will deliver more RPM at the cost of higher heat in the ESC. You could try playing with that. I've messed with it on my Vipers and I can't say I've noticed much difference.
PWM is only present at partial throttle. At full throttle, PWM ceases; the appropriate motor windings are driven 100% of the time. If a particular speed control shows a difference in full-throttle motor speed when the PWM drive frequency is changed, then there is something else (probably bad!) going on.