Just a thought -
I think my original alloy 851 exhausts had a ducati logo and a serial number stamped on them. If you had an ally plate made up with the number and logo and riveted it onto the carbon exhaust, would you then be able to say to the m.o.t. inspector / traffic cops that you were convinced that it was the original exhaust?
If so I might be able to get some made...............
Phil