i was on the way to work today and i got there and noticed a rattling sound coming from under my car. it almost sounded like marbles rattling around in my exhaust. its a 94gt with 165K on it. completely stock except for k&n filter, and weld-in flowmaster mufflers. anyone know what this could be?

 

im guessing that you still have the stock midpipe?? sounds like a bad catalytic converter.