Thanks vette.

I chased the threads with a tap I borrowed from our machine shop. I'm good to go without the epoxy now.

I don't know what temp the crap was rated for. It was a muffler bandage kit that I picked up at AutoZone. Rekin I got what I paid for.

The main reason for posting was to see if anyone had a clue as to how much back pressure was normal. During the fix, I cranked the engine with the O2 sensor out. I was able to hold the hole closed with my thumb (for a few seconds - it gets hot quick). I think we're good to go for now. We may ditch the cat & put on glass packs this summer anyway.