After blowing out a couple the super-duper gaskets, I went with Mark Algazy's recommendation and used a Toyota OE J-tube gasket with a healthy dollop of Orange RTV on both sides. I have the SOR SS J-tube. So far, a year and a half later, no problems. For the Exhaust donught-gasket, at the CAT/collector ends, I used a fel-pro. Looked just like OE. Also a bit of permatex, but I doubt the permatex will last very long with those temps. Anyway, no issues, so far.
OEM on the collector gasket is Ishino, if that matters, and available thru partsgeek.com I got the fel pro from NAPA.