There is no room for fins - the diff cup is aluminum and the slipper-side endcap has vents to promote better cooling, though. Slip generates heat, but the components can withstand very high heat without detriment. As Harold said, unless it is affecting handling in a negative way, I wouldn't sweat it too much. :-)
Last edited by RC-Monster Mike; 06.20.2012 at 09:37 AM.