tii muffler help

[Steve73tii]

Quick part /part # question: Is this the factory tii muffler? Mfg by Boysen, part # is 18 12 1 103 939. ETK lists a 739 part number, not 939.

I'm sure it's just a new # for the same part and it probably doesn't matter whether it's Boysen or Eberspacher. I'm just double-checking since I have gotten the wrong part from the dealer before.

Sorry if it's been covered, but the forum search yielded a wealth of other info.

--Steve

[Steve73tii]

I think I found the answer. There are 2 drawings with 2 different rear mufflers for each car, but apparently this is one of the non-tii mufflers. I'll have to re-order.

--Steve

[wegweiser]

From my books, the part numbers are as follows. I distinctly remember that the tii mufflers were an OVAL cross section, whereas standard 2002 mufflers were round. I'm not convinced there's any performance/sound/flow difference between the two. I'd feel comfortable installing a non tii unit on a tii, if cost effective. It IS interesting that touring tii uses a different muffler than carbed touring, too....there must've been *something* whiz-bang special about the tii rear cans....just don't know WHAT.

pre 75 (side exit) part numbers:

standard muffler very early 2002: 18 12 1 103 938. Manufacturer not listed and used until USA VIN 1660343

standard muffler most 2002: 18 12 1 103 939. Manufacturer not listed and used from USA VIN 1660344.

standard muffler most 2002: 18 12 245 484. Manufactured by Gillett used from USA VIN 1660344.

tii muffler: 18 12 1 108 739.

Original BMW muflers are manufactured by Boysen (not Bosal) Eberspracher, and Gillett.

OH! and Max's site as well as RealOEM.com show part number 18 12 1 245 523 as being correct for (let's say - a 1973 US) non tii - but that's only the number for CENTER EXIT 75-76 cars (!)

I've installed a whole TON of 2002 exhaust systems over the last 20 yrs - and the Ansa / Bosal stuff never seems to fit as nicely as the Genuine BMW stuff. Hanger locations, bends, etc are always just a little "off". The Genuine stuff definitely seems to last much longer also.

Hope this helps!

Paul Wegweiser