I had a custom cat-back stainless system installed on my c280. I was told that the center muffler (resonator) was the key to producing the sound I wanted without making the car excessively loud at highway speed. They used a universal Remus muffler and the center resonator is about 2.5ft long. The sound at idle has a bit more of a bass rumble than stock. Around town there is noticably more noise, but it is a very pleasant note. When you really open it up, it howls. Very nice. I think it comes off the line slightly quicker, but that is strictly a subjective thing.