Unless Mercedes has changed its policy the dealer should be able to remove your trap oxidizer and install another little things; looks like crummy tin foil.
But, when you drive away it will feel like you picked up 20 bhp and it is all legal! Elimination of the trap oxidizer reduces back pressure materially. A week after I bought my 87 300D (used with 40k) the trap imploded and took the turbo with it. I was getting on the freeway and stepped on it and the car kind of went "pfft" and a bunch of black smoke came out the back. I limped to the dealer barely able to hold 50mph. It was repaired under warranty the same day. The oxidizer removal s/b done free of charge.