Use a smaller pinion on the motor.if you have plenty of power to spare then putting a smaller pinion on will give you better motor temp and duration.
It is morre beneficial to the user to set the headspeed of the motor using the gearing rather than using the tx to drop the throttle range as you really want that motor to run at its peak to be efficient and powerfull at the same time.
More spped is not alway more power if you cant handle the first corner!.