Reader's Digest/ADD version: How do I make sure the catalytic converter gasket seals properly? Hey look, something shiny!
Full version: Last year I pulled my header out to try and fix some heat shield rattling. When I re-installed, gave the flange surfaces at the cat a scrub with a wire brush and then put in a new gasket. Turns out I hadn't cleaned it off nearly well enough, there were exhaust gases pouring out of the joint. I ended up getting in there with a screwdriver and chipping away old gasket chunks. Then I tightened the bejesus out of the bolts and re-used the "new" gasket. That got the leak down to a very low level, but it's still there. I've put up with it for a little while, but I have my inspection coming up and would like to avoid flunking. Plus, I'm kind of anal-retentive. I pulled out the cat this weekend and took a bastard file to both flanges. The faces are clean now, and I purchased new hardware. Any other suggestions for making sure I don't get leaks? I saw one how-to that suggested hi-temp permatex sealant. Anyone use that with success? I have the orange stuff that is pretty robust, but I'm not sure it's rated for exhaust temps. I thought the gaskets themselves should be capable of sealing, but if the flanges are distorted from 20 year of heat/cool cycles, maybe they need a little something extra.
If it helps, the car is a 1992, 1.6L.