Just my .02...............but if you have a cc limit of 0-500cc then you need to stick to 0-500cc. If you start letting other bikes in just because, that is going to lead to disaster...........somebody is gonna get butt hurt over the deal and there will be a scene. It does not matter to me what the cutoff is, but whatever that cutoff is you gotta stick to it. After that you gotta go on the honor system and trust people are gonna be honest with what they have. As for me I will have a little 403cc stock stroke.............BRING IT!!!