I think it looks odd on the squarish 124 and I hate fake dual exhausts - but to each his own I guess
I would rather do a nice Remus muffler with two rectangular chrome tips or oval tips.
I had a Lorinser muffler with two oval tips on a 230E. That thing sounded horrible :p It made a nice *I was young back then* rumble off line but at cruising speed (80+ mph) it also made an annoying buzzing sound...
probably just some 4-cylinder magic
:p
now I kind of want to release some of the burble from the 420's V8 but I really enjoy the car's smoothness on highway cruises. My friend who drives a brand new M3 thinks I shouldn't bother as the subtle V8 rumble sounds nice the way it is.
but anyway yeah.. if it was my car.. I wouldn't bother with dual exhaust and I would look into a Remus/AMG Muffler.
http://www.bergwerks.com/r_exhaust.jsp
call them up see what they got. Those guys know what they're doing. I believe you would need the first muffler on the list (for the 300E 12V)