OK, we have finally reached a conclusion on this whole mysterious issue.
My last comment on this was a few weeks ago.
I just got back from a trip, then had to run off to the MREA Energy Fair, and have been busy since then.
Right before taking off for the energy fair, I quick went to work on my exhaust system.
After 20 minutes of wacking, slashing, and whatever else I could do to get the exhaust, muffler, and catalytic converter off there, I had the muffler in my hands and it made a rattling noise!
Want to guess what was inside?
Here's a hint:
Apparently, a couple of chunks of catalytic converter broke loose and then wedged themselves inside the intake end of the muffler. Notice that the once piece at least has the holes going the right direction, but the other is at a right angle!
This must have been the equivelant of a potato in the tailpipe!
I still need to completely remove the cat and replace it with some plain straight pipe to keep any more chunks from breaking off and getting into the muffler again.