savagesam, do you have a good fan blowing on your motor?
I'm geared around the same as you (84/20 compared to your 81/19), but my motor is only a little warm after a 6 minute race. My ESC (orion r10) is usually warmer than the motor (ReVtech 6.5). I do have a fairly smooth trigger finger from racing mod TC though. Maybe the small amount of boost I have could be helping the motor to run more efficiently as well. More rip out of less throttle? I don't know. works for me
Anyway, it's an awesome car. I've been having a blast racing my XB4. The only thing I would change, would be making the wing mounts a bit more reinforced at the back, but ever since I've been shoegooing an extra piece of lexan under the center of the wing, I haven't snapped the back off any mounts. I broke a few before doing that though.
Wease, I run all my motor wires and one battery wire under the front drive shaft. It's a small channel there, but they all fit. Nothing is close to touching the spur on my car. It probably helps that I'm using a low profile servo.