Slow and wobbly wrote:In short. No.
In long, they could be. Anything can be repaired but there are 3 factors - Money, time and effort.
...says the man planning to resurrect a ZX9 which, at present, looks a lot like an exploded parts diagrams from a workshop manual.

Probably why he's so correct...
Partly because I'm a grot, and partly because I frevently believe that crash damage on your bike makes you ride faster and discourages thieves, if I had a set of mufflers like those, I'd just leave them. Those are significant dings and gouges, but they're just dings and gouges, not like they're likely to affect the functioning of the mufflers...
Fixing damaged muffler sleeves requires disassembling the muffler, rolling out any dents, then polishing out the scratches; if the scratches are deep, filling them in with weld may be required, and that takes a lot of polishing. With Staintunes, not only are the end caps welded on instead of rivetted, they use internal baffles for silencing instead of just wadding between the perforated core and the sleeve; that means a lot of careful cutting at the start, followed by a lot of rewelding at the end... end result, way too much effort for it to be worthwhile. If it was a Z1, and those dents were in the original factory 4-4, maybe you'd break a sweat, but Staintunes on a crashed ZZ-R600...