Did this this morning and still couldn't pinpoint it. On decel I get a slight backfire. I can't find the hole for the life of me. I'm gonna just ride it out until the hole is very apparent.Might be rusted right in between the flange ends, like a rusted out steel gasket or donut, making it very difficult to see. If the exhaust is still cool, you can carefully put your hand over it and feel exhaust blowing out. Can exaggerate this by blocking the exhaust outlet itself.
I have found the same issue. No one would put on parts I purchased on my own. My exhaust started breaking only 4 years after I got the car. Now in year 6 it is pretty much non-existent. I think the only thing that might be left under my car is a swiss cheese looking catalytic converter pipe.I spoke to some mechanic, they would not use customer provided parts. I am kind of stuck at the moment and seems like I will have to settle down at 700 without replacing catalytic convertor but replacing everything till back exhaust pipe. It is pricey but its been more than a week and can't find anything better in this town.