Since I'm running the stock vxl system, the motor gets pretty hot even with a heatsink and fan. I found this motor mount plate with heatsink on ebay, and was impressed in helping keep the motor cooler. I don't have a temp gun just going by feel, but after about 35 mins of bashing in the grass (13/54 gearing with 2s 45C 6000mah, day was 78 degrees) I can comfortably put my finger on the motor and not have it catch on fire . I think I will get the Traxxas aluminum motor mount next to help dissiapate the heat even more.
So just an fyi on those out there still running the stock vxl system.