I want to get an extra rear disc for my 07 wr450. I have a Supermoto conversion kit on it and want to mount another disc to the Supermoto rear wheel instead of changing back and forth... First question is.... does the 06 rear disc fit on the 07? The non wave roter is probably less expensive I figure.... secondly are aftermarket rear discs less expensive since the OEM is about 90 bucks for the rear which is pretty steep. I don't really care if its wave or not because on the street I use the rear way less. Just looking for a better price.