How to keep exhaust legal (CA)?

[jmz135]

Hi All,

I am fairly new to exhausts (and also new to california) so I'm a little confused what is and is not illegal here...I installed an aFe axleback yesterday and want the car to be louder but read in another thread that replacing the midpipe would make it fail carb/smog here in california?

Is the piece right after the axleback that I unbolted the oem muffler from the catalytic converter? I think I've also seen it called a resonator? Are they the same thing? Or is the cat part of the downpipe?

If the cat is part of the downpipe can I safely put in an aftermarket mid-pipe and be legal in california?

Thanks for the help!

[135ilust]

Originally Posted by jmz135

Hi All,

I am fairly new to exhausts (and also new to california) so I'm a little confused what is and is not illegal here...I installed an aFe axleback yesterday and want the car to be louder but read in another thread that replacing the midpipe would make it fail carb/smog here in california?

Is the piece right after the axleback that I unbolted the oem muffler from the catalytic converter? I think I've also seen it called a resonator? Are they the same thing? Or is the cat part of the downpipe?

If the cat is part of the downpipe can I safely put in an aftermarket mid-pipe and be legal in california?

Thanks for the help!

Well it all depends where ur second cats are. If they are in the dp(like how mine were) then u can get a race midpipe and remove the resonator without any emission problems.

[jmz135]

Originally Posted by 135ilust

Well it all depends where ur second cats are. If they are in the dp(like how mine were) then u can get a race midpipe and remove the resonator without any emission problems.

We both have N55s so our cars should be the same as far as exhaust goes...so the car comes with two cats? One in the dp, and where is the other? Part of the resonator?

[135ilust]

Originally Posted by jmz135

We both have N55s so our cars should be the same as far as exhaust goes...so the car comes with two cats? One in the dp, and where is the other? Part of the resonator?

For my car the primary cats and secondary cats were in the downpipe. So as long as I don't touch the downpipe, any exhaust work should be emission legal.

[Cavpilot2k]

You are correct. The N54 had a secondary cat in the midpipe, but the N55 does not. So you will not affect emissions by changing the midpipe and muffler sections.

Technically, however, the answer to your question is that you can't, as any modification to the exhaust system for street purposes is illegal, especially in CA. BUT, everyone does it and it is only enforced if you give someone reason to give you a hard time.

[jmz135]

Originally Posted by Cavpilot2k

You are correct. The N54 had a secondary cat in the midpipe, but the N55 does not. So you will not affect emissions by changing the midpipe and muffler sections.

Technically, however, the answer to your question is that you can't, as any modification to the exhaust system for street purposes is illegal, especially in CA. BUT, everyone does it and it is only enforced if you give someone reason to give you a hard time.

Great, this is what I was looking for, thanks! Yea most things are technically illegal in CA - but as long as I can pass emissions with an AM midpipe that's good enough for me...cheers.