No one is making exhaust system for the 1992 to 2003 cb750’s.
bikes from these years are in the junk status not collectible worth no money!!
I love mine no valve adjustments fun bike.
Mack at some point made an exhaust for these bikes - check eBay you may find a used aftermarket exhaust.
lots of stock exhaust for sale on eBay ( the garage sale to the world)