Also if you don't have hfc's/test pipes you can get ones that already have extra O2 bungs (fast intentions does this) and it comes with a plug so you can run them before installing the gauge if need be

Thanks for the input. I've been e-mailing Fast Intentions, and while they've been helpful, they won't provide the mil spec cats fabricated into the lead pipes without purchasing the whole exhaust system. They'll do the bungs in the test pipes, but I have to know ahead of time how many to ask for. Thanks for confirming the plugs...

I purchased 100 cell cats directly from mil spec, I'm having them welded into my lead pipes.