The exhaust was shot in my 1980 280SE when I bought it so I had a local muffler shop fabricate a replacement. It was way too "burbly" and would resonate in a narrow rpm band. A few months ago I started collecting parts to convert to a true dual exhaust and finally started this weekend.
Here is a video of the exhaust the local shop made for me:
http://www.youtube.com/watch?v=msvedVKQg4o
I'm waiting on a set of manifold gaskets to arrive and then I'll put it together and see how it sounds.