I am running a MM5700 in my XXX-T. With my 3s lipo I like to gear it at 15/86 and when running my 6 cell IB4200 pack I like to gear it 17/86. This gearing keeps my motor temps down around 180 degrees. I am sure that I will have to make some changes once summer gets here and things warm up. Just take a stab at the gearing and then check your motor/esc temps until you find your sweet spot. Good luck!