usually the problem is not flying about, mostly it's hitting the pipe.
Yes, that was exactly my problem also. I have a 4-1 that had a noticible upturn on the pipe so that the RH bag would hit. Then I snagged a set of damn-near-perfect 4-2 mufflers, but I have only 4-1 pipes. Then I started looking for the 4-2 pipes to go with when two things occurred to me:
1. This was getting pretty extensive & expensive for a set of old bags that I got as an experiment.
2. My muffler was connected to the header with a clamp that I had never noticed before. Duh.
So I loosened the clamp and spun the muffler so that it was more level and less upswept. Double duh.
Well, I ended up painting the rusty/crusty old muffler so it looks nice (pic was before the paint job..), and at least I now have a set of really nice 4-2's for someday when I can score a set of headers to go with 'em. <Insert heavy sigh> sometimes it's painful to be a noob.