you need to keep an eye on the forum on
www.teamtekin.com as there is some gems of information on there, and don't be afraid of asking.
It doesn't need a heatsink, the solder posts ARE the heatsink, and if you are getting thermal problems, then you NEED to cool it, simple as that, but in off-road, they find that mostly you don't. when you are running, what is the temp indicator showing on the LED's?