The pipes are aluminum and so can be massaged back to a nearly new condition with some basic effort.
Here's a shot showing the upper muffler after a quick buff with Mothers polish.
This closeup shows how nicely the finish can be transformed with very fine grit wet-sanding followed by hand polishing.
Let's see what we can do with this scratch.
First, I wet-sand with 400-grit till it disappears, then continue with successively finer grades up to about 2000-grit.
Then several applications of polish till it matches the surrounding area.
With the exhaust pipe's fresh coat of VHT black paint, this system will not only sound the part, but look it too.