Mate, I am running a 13/47 combo with 100mm tyres with the .12. While top speed is 40+ mph its a little slow on the take-off. With a bigger engine it would pull it easily. An 11 would suit mine better. Oh and I am just running the front end 4WD style but without the diff and dogbones, mine started out an MT2.

EDIT: Axle #FF059