Not all high-flow cats will pass emissions. Most of them don't gaurentee they will. I use test pipes, and switch to cats for smog. Not really a big deal if you ask me, since our cars are new, we don't gotta smog for like 6yrs or something anyway.

My other car, 91 MR2, has to smog every other year, and is test only, everytime. Switching the cat back and forth on that thing is a PITA!!! But on a turbo car, the cat robs literally 20+hp, so still worth it, IMO.