My 2002 E320 with 34,000 miles started making a knoking sound coming from underneath which is loud outside the car at idle. I put the car on ramps and when I bang on the softball size cat converter or resonator or muffler on the passenger side which is the one with the flex bellow device it makes the knocking noise. I removed all the hangers and tried to adjust the exhaust to no avail. The noise sounds more like a knock than a broken baffle. If I go to my MB dealer is this still covered? I purchased the car from the MB dealer used 1 1/2 years ago. Thanks for any advice.