Why not go cat-less? Seriously. Phuch what CARB says. A well-tuned vehicle can meet emissions standards without one. Hell, a friend of mine met emissions standards with a HIGHLY race-modified 951 - no cat. Of course the smog-nazis didn't care that he beat the tailpipe emissions handily. Results don't matter with CARB and the smog nazis - only drone-like compliance because they know what's best for you.
Sorry to hear about this. Maybe just do what he ended up doing - get a cat shell and clamp/weld it around a pass-through straight pipe.
He passed the visual AND the emissions test this way BTW.