That's a shame as they were a unique, reasonably priced system. As Halfmile mentioned Gunn & Jemco will perhaps make you pipes. I have a set of Gunn Design (attached); top-quality, but expect to pay in excess of $1K. I haven't dealt with Jemco - they have the capability (see website).
Another option is back to the MAC knowing you'll have to re-fabricate the left head pipe: not too difficult given tools and a "builders kit" (that includes pre-bent pipe sections to weld), just make sure the kit pipes are the same diameter.
https://gunndesign.us/#home-section
https://www.jemcoexhaust.com/gallery.html