And this is for the cyclic and tail servos? There are times that the tail servos will not handle the voltage of the cyclic servos. But, if all of your servos will handle a straight 2s pack, then you can set it at 6 and go from there. If you want to get risky just to see what happens, you can set it to 7, but don't go to 9 as I'm sure nothing can handle it on there. Just make sure to feel for heat in teh servos. If they are getting hot, then you are over volting them.