ORIGINAL: DarkWombat
Well you have to be using a LiPo pack as well, because the stock battery pack only delivers 9.6 volts while a 3S LiPo pack delivers 11.1 volts, so the motors are spinning faster. To keep the main motor from burning out from high amperage draw, you have to use a 9t or 8t pinion gear so it is not working as hard, but with the smaller pinion you'll be getting more torque and speed because it's more voltage, but the motor isn't drawing too many amps. This is why you also have to put on the heat sinks so the motor doesn't burn itself out from the higher voltage. So yes, using a 9t or 8t pinion will give you improved performance if you're using a LiPo pack. No use in going to a smaller pinion if you're not using a lipo pack because you won't get as much torque, and don't stay with the 10t pinion if you ARE using a LiPo pack or you'll burn out your motor.
I see now. So it does decrease head speed by changing the to 8 or 9T from the stock 10T, but with the added voltage it bring you back up to where it needs to be. I have put 3 flights on my blade with a 3c lipo with the stock motor. I guess I am lucky I have not burned them out. I am using the heat sinks though, so maybe that is helping. I will swap mine out with the 9T before my next flight. The head speed was really ripping with the 10T a 3c lipo though. It was rock solid as well. It will definately go inverted with a lipo.