MB Cats are just as crap as aftermarket. I had one cat go on me at around 80,000 miles, so the tech replaced it with an aftermarket cat. 3 months later, the car ran like crap again and it seemed to be the cats. When the muffler shop pulled everything apart, they found that the pre cat (also MB part) disintegrated and destroyed my new one.

It turns out that the right side cat on these cars has a known issue and ofcourse, no recall.

I replaced them both with another set of after market and have had no problems in the last 30k miles.

__________________
With best regards

Al