OLAAL

Yesterday I installed the etrailer trailer hitch I had previously had on my 350RX onto my 2021 450H. Following the instructions, I had to cut away a small portion of the underpanel in two places but all went well. Today I noticed a distinct lower frequency engine/exhaust sound when the hybrid is using the gas engine, specifically when the switch occurrs from eco (electric) to power (gasoline). I cannot believe that in carefully making the installation -- I did have to disconnect the rearmost tailpipe support, slide the bar between the tailpie and the underbody, and then reconnect all -- that I caused any harm to any of the connections in the exhaust system.

The exhaust pipe does just touch the trailer. Could I be getting some sound transferrence from the tailpipe touching the hitch assembly into the hitch assembly causing an echo of sorts, or did I actually do some damage to the exhaust system?

geko29

The bolded part is almost certainly right. There should be some clearance between the exhaust and the hitch. Double-check the exhaust hangers and make sure they're all connected correctly. See if the hangers are adjustable at all. Also see if the hitch can be moved slightly to provide clearance.

If all else fails, you could put some heat-proof padding in between the exhaust pipe and the trailer hitch where they contact each other. But I'd definitely contact the hitch manufacturer first to talk about what you're experiencing.

OLAAL

Thanks. Putting in a heatproof pad has eliminated (most) of the noise, but it will wear down over time and probably will have to be replaced every month or three.

I spoke to the hitch mfg and they confirmed that is the right hitch for the hybrid. So they took the report and may or may not update their information about this vehicle. The hitch is mounted properly and the bolts are tightened to the proper torque. There is no additional clearance that can be gained by more tightening. I will visit an exhaust shop when I have time and will see if they have an option to replace either the rubber hanger or the metal support from that hanger to the body to gain the bit of clearance I need. I am sure something safe can be jury rigged, but not easy without clearance and I dont have a lift.