Originally Posted by ercwhtsd

The original intent was to dis-allow the "optional" permanent heat sink/fan made by Novak which required the motor to be physically taken apart to install it. The use of any other optional heatsink fan has always been legal, with the exception of the LRP model that had a 40mm fan.

It was also implemented to dis-allow the light weight, vented, optional internal fan assembly made by Eagle racing and sold thru Integy.