I can imagine how hot yours is getting.. my buddies 7700 on his mf1 we think is getting the transmission very hot thus heating up the diff gear and making the diff balls waller it out easily and strip it out from the inside out... with him running a 18/86
I'd suggest a 15 or so... I run a 16 and with a 18 it gets a little warmer but a lot faster
Hows your buggy holding up besides the temp issue? belt working alright, looking at getting one but didn't know how it would hold up with the brushless in there..