If you have a good battery pack the HS 5645MG pretty good choice. At 6 volts it kicks down 168 oz of torque and 143 at 4.8 volts. If your using a plain battery or a 1000Mah rechargable your better of using an analog rather than digital servo......which is the HS 645 MG that works out at 6 volts 133 oz and 107 oz at 4.8. Not great but not bad either..........Analog the batteries last a lot longer and the servo is a lot cheaper. My self I run Airtronics Bone crushers and I don't even like to think about the price[:-]