CJ. You do welding?
Today's thought is a universal muffler mount. Basically, an H-shaped shell that mounts like the shell of a stock muffler to the bike, with fairing mounting points. Then, have a universal X" bend from the header to the center of this section.
Basically, people can pick and choose their own generic mufflers from ebay or an auto parts store, slide it in the "cage" you built, onto the header adaptor you made.