Nobody seems to be responding, so I'll try to help. Power (speed) is somewhat proportional to voltage, but you don't want to change your battery and your controller might not be suitable for more voltage anyway. You could try a different wind motor to provide more speed, but your present system is probably set for optimum efficiency in its configuration. The torque (acceleration) might be compromised or the engine might run much hotter. Try endless sphere; they are experts on more speed.