Originally Posted by James35

You will get sintered rotors from now on. Charles from Novak has confirmed they are no longer making the 1st and 2nd generation 13.5's. The new Pro version is the current production model and it's being sold at the same price. Differences are: sintered rotor, ribbed can, colored timing ring.

Those are the only differences, so purchasing a sintered rotor to put in your old 13.5 will produce the same power as the new Pro version.