That exhaust would put me off ,I drove one with an aftermarket cat back section and it sounded dreadful .
The R129 is a very quiet car and for me a shouty exhaust doesn't suit , a genuine replacement is not cheap either..
The rear box is important ... MB ones are pretty refined. I had the centre muffler removed (MB dropped this in the '99 facelift anyway), and it made only a tiny difference to the sound.