Guys just had exhaust mod on my 55 AMG and it's the best thing I have done. Used a local exhaust manufacturer called Cybrand. They are based on the Wirral and formally know as Peco that made exhausts for rally cars and boy races in the 80's .... Anyway, took it into him and when we checked it looked like someone had already removed the 2nd cats but not fitted the X pipe. They made up a X pipe from stainless steel and completed the whole job and all for £200, bargain. I was worried that it might drone on the motorway, but it seems no different when cruising at just above the legal limit ? But when you open it up it now it crackles, just like a C63, this should be standard at the factory as you don't buy a V8 not to hear it. Mark at Cybrand is happy to help anyone else who is interested in the same mod. If you have a 55 and not done this mod I just have one question..... WHY? ?