I put mbrps 4inch exhaust on my truck and it resonated so bad it hurt my ears. After some Internet research I tried putting stainless steel flat bars on the pipes and muffler held with hose clamps. That lessened it quite a bit but at times was still too much. So I ordered a braided flexible coupler from amazon, I welded it in the 3inch section after the y pipe and before the 4inch pipe started. Since then no more drone just awesome exhaust note.