I'm not sure. A mate reckons he can weld something straight onto it and then use a slide hammer to pull out the dents.
I've also been looking at painless dent removal techniques on YouTube (amazing stuff, some are really worth a watch). Dunno if it would work on something so creased and on such a tight curve though. I've put an inspection camera in the muffler and the internal space isn't compromised, though I guess some of the layers of deadening must be squished. A final option would be to remove the end cap and internals and then force the dents out from the inside. I think I could cut circles out of ply, attach them to stud again and work my way down to the narrower part in a series of smaller and smaller discs, but I think it would be laborious.
I might just test the exhaust at this stage and see what it's like. The whole system only weighs 5.5 kgs so this would mean saving another 3kgs + over the twin carbon cans I've got on the bike at the moment.
The other option is to fit a road legal silencer onto the Arrow manifold, which is kind of of why I bought the system. I think there's a place local to me that could knock up a link pipe for me once I find something I like. If I could find a secondhand HP Corse Hydroform at the right price is be very happy! Technically there's no rush above and beyond my basic level of impatience!