Been looking at this:
www.aa16.co.uk/a16exhaustparts.htm With carbon cans at such a high price, whats to stop you buying all the bits and making them yourself? After all, they are just a perforated tube packed with sound deadening inside a carbon tube....aren't they??
I'm sure its too easy and there must be a good reason why this is a ridiculous suggestion, but I can't think of one.......