Funny you should mention this now. Only last night I was reading an MB factory publication from back in the '80s (lent to me by another MB club member) that covered all the features of the then new 190E 2.6 (with M103). One item mentioned was the fitment of a small muffler in each of the two engine pipes ahead of the underfloor catalytic convertor. I too always assumed that they were pre-cats. Both my '90 190E-2.3 and '90 300TE have them but I have never investigated as to what they contain. I know that if they are pre-cats, I would prefer they were not there, especially after Gilly and others have mentioned that their failure can lead to engine damage, especially on the M102.

__________________
107.023: 350SLC, 3-speed auto, icon gold, parchment MBtex (sold 2012 after 29 years ownership).
107.026: 500SLC, 4-speed auto, thistle green, green velour.
124.090: 300TE, 4-speed auto, arctic white, cream-beige MBtex.
201.028: 190E 2.3 Sportline, 5-speed manual, arctic white, blue leather.
201.028: 190E 2.3, 4-speed auto, blue-black, grey MBtex.
201.034: 190E 2.3-16, 5-speed manual, blue-black, black leather.