From what I understand, the exhaust from my M50 should have (this is post-cat pipes, connecting to muffler pipes) two metal exhaust flange gasket rings to seal off the system... However it appears that one of the lip/rims is not there.
here is a picture (not mine.. but same issue) Bimmerforums - The Ultimate BMW Forum
I purchased two rings from the stealer and the diameter is not big enough to fit over the pipe... did I pick up the wrong one? I used the PN from realoem.com