I spoke with the guy at impaktrc and he recommended a 1512 2.5d for my e-revo 4s setup. Received it today and took it for a blast tonight.

Temp didn't break 140 on the motor after driving for 30 min straight. I'm using a mm with ccbec. I tried a 19t and a 21t. The temp difference was 7 degrees. I cannot believe this motor compaired to my 8xl. I like 21t MUCH better. It was much more driveable on the track.