I did remove some material from the mount a bit (maybe 1/8"), but was concerned about taking too much away and creating an area that might be weak. I think I'll just mount the muffler and see what happens. Maybe I can slip some nomex in there if I can find a scrap of it somewhere. It would be difficult to flatten the muffler as it is a Slimline smoke muffler and that section has the smoke coil in it. I don't want to damage that in the process.