Thanks for the input guys. I made a code reader last week, and will finally have a chance to use it today. I'll post the results.

It'd be nice if this was just a clogged cat. The car does seem remarkably quiet for having just straight pipe aft of those two cats...

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'85 500SEL, 245,000 miles (sold)
'92 400E, 295,000 miles (donated)
'84 VW GTI (work in progress)
'10 VW GTI (daily)
'72 Chevy C10