Recently replaced the exhaust (from back of convertor to rear) on my 04 MC. Passing along my experience to benefit others.
Stats: 04 MC, production date 11/03
Intro
I could have done the job myself, but now that I have all the tools I need and money, I have no time. So yes, I know, I paid too much.
Parts, Labor and Costs
Went to Car-X. They used Wagner replacement parts.
Parts:
#56141 Quiet Flow Muffler, $459.41
#52323 Exhaust Pipe, $177.45 (this is the resonator)
#34200 Bulk Clamps, $2.99
#31534 Gasket, $11.91
Labor, $80 (of course they made all their money on the markup of the parts)
#18-20-7-520-245-M61 Muffler Clamp Kit, $53.25, plus $12 shipping (Car-X didn't show this part, thought it would come with the muffler, it did not. I ordered it from Pelican Parts after first looking up part # on realoem.)
Realoem: http://www.realoem.com/bmw/showparts...77&hg=18&fg=20
Pelican: http://www.pelicanparts.com/cgi-bin/...t%20Hangers%29 (It's part #11 on realoem, even though DESC reads "CLAMP UPPER", it's the kit which includes upper, lower and rubber bushings. Everything you need.)
Bumps-in-the-Road
1st trip to Car-X, after initial phone call: didn't have parts, had to order from warehouse. 1 hour roundtrip.
2nd trip to Car-X (later that day): parts arrived, no clamps. Car-X not sure where to get. Another 1 hour roundtrip.
3rd trip to Car-X (1 week later after the clamp kit I ordered arrived): arrived at 8 a.m., work started at ~ 8:30 a.m.. Completed at 10 a.m.
New parts too long, Car-X had to trim and weld at back of resonator to rest of exhaust. But Car-X did a good job.
More Info
Amazon has same Wagner parts cheaper, free shipping:
http://www.amazon.com/Walker-Exhaust...3858487&sr=8-1 $178.32
http://www.amazon.com/Walker-Exhaust...3858567&sr=8-1 $65.52
Pelican has OEM resonator/muffler, all 1 piece, $532.75 plus shipping.

Hope this helps someone.
Jerry