What we need really is a new OE style exhaust system making out of stainless steel. In my experience they rust from the inside out, making them out of stainless would stop this. I was told by Honda UK when I was on a training course there that Honda had sold all the stamping presses for making the CB500 exhausts to a firm in China, this is where David Silver buys them from I'm led to believe. However the presses now appear to be getting worn and the standard of finish isn't anywhere near where Honda used to make them. I've got 2 sets of brand new exhausts stored away, ones a Dave silver job, the other OE equipment, you can see the difference when you lay them side by side. The OE ones are sharper in detail, brighter in chrome work and just look much better made.
Been a long time since I dug them out of the loft but I seem to recall the Dave Silvers ones were marked 374 instead of 323 like the OE ones.