Just installed a brand new Bursch exhaust from Pelican. Took about a month to get it delivered but I finally got it. I was interested to see if it really would sound nicer than my old, holey Sebring on my 73 2.0.
Switched it out and fired it up Sounds OK at idle, but when I rev it up a little, it sounds awful. It sounds like a buzzing or vibration/rattle is coming from somewhere. I checked the gaskets and did not find any obvious leaks. I checked the exhaust hanger and it is connected and tight.
Now what? How do I know if the damn muffler is bad? Do these things sometimes come with a loose baffle or something? I really am not looking forward to returning the thing and then waiting for another month to get a new one. Heck the snow will be flying here in a few months!

Warrenoliver

It might be touching your rear valence. Mine did, took a file and notched it, no more noise

If it's not touching the rear valence, take the muffler off of the collector & shake it... see if something is rattling inside.

mine does the same, just installed it and i get te exact same rattle. (brand new from performance prods.)

i thought that it might be the valance or actually contacting the lip of the chassis.

if it's loose inside, just send it back, eh?

is the muffler making contact with the heat shield under the trunk?

Mine was doing this when I first installed the glass pack.

Keep in mind these cars are all hand-made...

I checked the clearance around the muffler and pipes. No contact with either the heat shield or the valance. I took it off and shook it, but no rattling.
I can not hear it when it is idling, just when I rev it up. I will have to wait til my son is home to help rev it up so I can feel for a leak somewhere.
This is frustrating after the long wait to get it delivered and also the Pelican guys talked me out of the Sebring exhaust because the Bursch sounds much better!

Is it making contact with the back of the transmission?

I had a brand new Bursch exhaust do the same exact thing ~5 years ago. Turned out to be a bad muffler. Sent it back to Bursch for a warranty replacement and I got a new one in 3 weeks.

lose the valance.
show off the purty muffler...

+ removing the valance will promote cooling.
and its just drag.

-jim

Check to see if the warm air guides (sheet metal between the heat exchangers and crankcase) are tight. I have a broken tab on each side and sometimes one side or the other will rattle like a mofo until I bemd on it...