Ok, gang - the youngest measured up the factory muffler - the canister is 28-1/4 inches long! There is a double hanger welded to the exit end, and a single hanger welded to the entry end. Inlet & outlet is 3-1/2 inch diameter.
I have never seen a muffler monstrosity like this for a gas engine. I think a retrofit would be too much for me, and too expensive to pay a shop to do, so I think I'll just drop this effort.
I appreciate all the thoughts and wisdom. I will likely install ARH headers next, since the crappy factory manifold warps and breaks bolt heads anyway.