[L473ncy]

If you're going to go 9.4V why not go 7.4V lipo? They're cheaper, and provide arguably the same performance (except when you start to get Vdrop and that's when you change to a new battery and put the old on on the charger).

Also, always go for off the shelf drop in solutions (ie. complete gearbox), there's no point in dicking around inside the gearbox if you don't know what you're doing. I don't recommend the high speed motors because IMO they just make you into a BB hose, I'm perfectly fine with my TM EG1000 motor which nets me more or less what a RS AR15 shoots at (~750-900 RPM or 12-15 RPS).