hey,
I am currently seeking a heatsink for my loxi xcelorin motor (39mm diam.), I have found out that the losi-heatsink fits neu motors:
http://www.impaktrc.com/product_info...osCsid=d5e22ae
if you use a heatsink, use some thermal-paste. I used a novak HV heatsink on a 88mm long inrunner, and it lowered the temps definately (fits VERY tight and is heavy), for a good thermal transfer I use thermal paste. but in the end, the motor was a bit crappy...
of course, gearing etc. has to be right etc, furthermore, neu motors are top of the shelf stuff and are very efficient. but under racing conditions at high temperatures it could make sense.