After all these years when I do annual cleaning, I would replace the interam gasket around the cat as it would just disintegrate and need to be replaced. When I put the cat back in and I would wrap it with the new gasket, and it would make a nice fit, but there are these side "pockets" of maybe 1/2" x 4" that needed to be sealed too. There are these manufacture supplied looking cotton/asbestos looking pads that I got when I installed, and I would always reuse them and stuff them back in there as they seemed to be what was needed. I've thought they were doing the job, but this year they finally wore out, and crumbled. So, I just got more interam gasket, rolled them into pads, and stuffed them in those sides for those gaps. Wow, recently had a fire, I couldn't believe how much more of the cat was glowing. I think I was previously getting some fire bypass and leakage around the cat from those pads, but now since more tighter with interam gaskets, and when I engage the bypass, the seal seems better, and it's an improvement,
