Catless system's will not pass emissions. Even sport catalyst systems will not pass the actual sniffer test. Some states don't have sniffer tests, but the ones that do, catless systems will not pass under any circumstance.
If emissions is of concern, the best thing to do is get a louder exhaust system and keep the midsection stock.
MRF on Facebook
Southern California's largest & most reputable E9x M3 forced induction & suspension facility.