car in question is an E300D W124, problem is that the exhaust pipes resonate at 2500 rpm to 2800 rpm, The sound is not a hole, not the rear muffler, Me and several exhaust shops have tapped the whole thing with a hammer, magnaflow 16 inch diesel cat has been installed about 3 inches rearward from its original location (MB cat was huge)

I swapped out the centre muffler with a used one and still have that same noise. No shop is able to get me an answer for it. MB dealerships will probably tell me to junk the car or buy a new exhaust for about 2 grand. The front pipes and cat alone are about 1500.

anyway.. Have any of you faced such exhaust problems?

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2012 BMW X5 (Beef + Granite suspension model)

1995 E300D - The original humming machine (consumed by Flood 2017)
2000 E320 - The evolution (consumed by flood 2017)