I'd be surprised if a set of headers for our X's would be CARB legal. Why would anybody pay an extra 10 or 20k for CARB certification? You would definately fail visual inspection, however if you could reuse the heat shields, there might be a chance. Visual inspection is supposed to check everything between the cats and your engine, including the engine. Keeping the stock cats in, you probably would pass the sniffer, as long as everything stays nice and hot.