One problem related to manifold/header/muffler/tail pipe has been reported for the 2000 Mercedes Benz ML320. The most recently reported issues are listed below.
Within six months, both stainless steel exhaust pipes cracked at the welds, just ahead of the cat. Converter. In the first case, the pipe was replaced. In the second instance the pipe was welded (hopefully will last longer). With the second failure, while the noise increase was barely noticable, exhaust gasses leaked into the passanger compartment. As a professional pilot, I know the consequences of CO poisining.