The rules were written to include bikes that were raced in the AMA Superbike class. Even thought he 748 is a middle weight bike, it is only because of the CC's of the bike. The chassis and frame etc are the same as the 916 etc, this cannot be said for the Japanese middleweight bikes. AHRMA is not ready to do a 600CC class and may never do one. They were trying to be inclusive for the Ducati 748 because it is so similar. I will bet you if we left them out, people would be complaining about that. As for the cc limit of 996, there were several kits at the time for the 748 that you could buy. It was easier to just put a limit on that bike of 996 rather than list each kit that was once available.