I just put on a Curt hitch for my 2001 Honda CR-V, it went on okay with a minor problem. Part of the process was to lower the muffler, which I see was needed. Once done the muffler was rehung.
Now there is a noise, a rumble when letting off the gas. Is sounds like maybe a weld broke when lowering to raising there muffler, but I cannot see anything out of order yet. The weld at the front of the muffler LOOKS ok, I did not check it with the engine running. When driving it sounds closer to the engine than the muffler, but I know such sounds can be confusing as to location.
The hitch frame does ride right along side and touching the muffler, I can see maybe a source of some noise there, but not the rumble only when letting off the gas. I caught try putting a rubber pad or similar item in between the muffler and the hitch frame, do not know how to hold it in place. Maybe tie wire it from the right side of the car somehow, pulling the muffler off the frame.
Edit: I once more looked at all welded joints and all seem okay-- without running the engine. I started the engine and heard the noise. For a temporary check, I found a sanding block made of a hard spongy material. I put it between the muffler and the hitch frame, held on only by the pressue of the muffler against the frame. The noise went a way and revving the engine some then letting off the gas made no noise more than normal. Now to find something to put there permanently. Not sure what too use or how to hold it in place.