[ryandrake]

Not only are they required but CA requires $pecific ones with their CARB seal of approval. I had an older car from outside CA that never needed to comply with CA’s rules. When I moved to CA I tried to do the right thing by installing a working cat and tuning my car so it did not pollute. Got it to blow clean as a whistle but the state still failed me because it wasn’t one of their expensive approved devices. Ended up having to sell it out of state because CA labeled my car as “tampered.” You cant win with these guys.