Someone will surely correct me if I'm wrong but I believe the difference has to do with the mounting bracket in relation to the rear passenger foot peg so the old will not work with the new.

 

I don't think the exhaust changed...just the way the tune is installed...I recall a few people on here swapping various models without any drama...I'm not certain there are any problems installing the tune if it comes with one...if it doesn't...you can upload the tune yourself from a website...not free...but I think a rapid bike Evo thingy is the better solution...in any event your going to want/need a tune of some sort