Dacs, you're crazy...
The line you guys are looking for is missing on a lot of your profiles. It was missing from mine, but Slob kindly intervened a couple of years ago and added that particular permission, I think it also activates some others at the same time?
Re the exhausts; I think S/S has a tendency to weld itself together? I know that nuts and bolts can "gall" and seize. I watched my brother spin a nut down a piece of threaded rod once, it stopped and would not turn again. In the finish it snapped the rod when we gave it some welly with a vice and spanner!
Maybe if the pipes were a tight fit on assembly, they galled when they were belted together? I know that's not very promising regarding their separation!
I always leave my rear pipe firmly bolted to the head and then gently rock the front pipe from side to side to ease it off, but it's not seized and knows it's way off now anyway, but I still think that's the best way to hold it and apply force.