Some will call me nuts, but have you thought about a Novak HV motor. I'm running a 4.5 in my Slash, sensorless with a Quark esc. On 3s it's a monster, and never breaks 120. If you ran the 6.5 (3400kv ) performance should be about even with the others you ran, with no heat issues. You can get them remanufactured for 75$ , Just a thought.