I thought the thread was about something else. I guess I'll answer it while I'm here though.
Without the cat, it's hard to pass emisssions. The performance gains are extremely good though. One thing you can do is to get a test pipe with a cat. This way you can just bolt in the cat when you need it to pass emissions, then remove for driving. The cat is a slip on cat for the test pipe and just bolts on. Speedforce racing makes such a cat, but it's not on the catalog yet. The cat adn test pipe run $599. I've looked into this before too...
