[Ajowhan]

Looking at the exhaust on m240i, There doesn't seem to be any 2nd smaller catalytic converter on the midpipe. Instead, It looks like we have 2 resonator only.

Does this means that the m240i is one of those car that we can do a catback exhaust and still be smog legal in california?

[MarcoZandrini]

Non-turbo's BMW 6 cylinder engines were "split" into 2 banks. Each bank Had its own catalytic converter and oxygen sensors. My old 330Ci had 2 cats and 4 oxygen sensors. The M240i breaks from that "splitting" and treats the entire engine as a single entity. Hence, it has a single converter and 2 oxygen sensors. Anything downstream from the cat is either a muffler or an resonator. Can you install a cat back exhaust in a CA car? Check with the California Air Resources Board (CARB).

[Ajowhan]

Originally Posted by MarcoZandrini

Non-turbo's BMW 6 cylinder engines were "split" into 2 banks. Each bank Had its own catalytic converter and oxygen sensors. My old 330Ci had 2 cats and 4 oxygen sensors. The M240i breaks from that "splitting" and treats the entire engine as a single entity. Hence, it has a single converter and 2 oxygen sensors. Anything downstream from the cat is either a muffler or an resonator. Can you install a cat back exhaust in a CA car? Check with the California Air Resources Board (CARB).

So after further googling, found out that even a muffler or resonator delete is technically illegal in CA.

Just wondering now if anyone has done catback on m240i and pass SMOG test.