Hi, all. Please share feedback on California CARB exempt exhaust systems (headers and cats, with the understanding that downcat mufflers don't invoke smog issues) you've experienced on any non-turbo 996. In particular, how it sounds and difficulty of installation would be useful for those of us looking to put together a good sounding exhaust system for our 996s. There are several threads on CARB compliance for turbo 996s, but this thread is specifically for non-turbo 996s.

Please don't respond with advice on how to skirt visual inspections or with non-CARB exempt systems where you didn't get caught during smog checks. This is for 996 owners who are looking to do stuff legit through and through.

To kick things off, I'll start with what I've found. Apparently, the ONLY direct fit catalytic converters that currently have CARB EOs are the Magnaflow 444066 and 444067. Both of these are sold on Amazon for less than $600 each, but neither YouTube nor the rest of the Interwebs appear to have much info on how these cats sound or how difficult they are to install.

Thanks in advance!

 

There is a lot of muffler after the converter and before the exhaust outlet. Hard to imagine converters would have much if any effect on sound. My main concern would be that the new/replacement converters 1) are legal so there would no hassle in getting my car through a smog check; 2) are efficient, don't trip a CEL P0420/P0430 intermittently (make that any); and 3) last.

 

Since Macster replied I will chime in.

As a former CA native you have two choices. Find a coupon taking SMOG shop, they likely don't give a crap. They spent a ton of money on the failed rolling road machines and now CA figured out that OBD2 reporting is enough.
OR
Waste a tons of money on following the rules to the letter of the law. Don't just go on eBay and find matching OEM cats if yours have failed or put on any proper length and diameter aftermarket cats. Sure those will resolve the emissions and pass with flying colors but gosh you are breaking the CA SMOG police laws.
You must buy OEM new parts for your car to one bazzilion dollars.

 

CARB is cracking down on SMOG shops that don't "give a crap". There is much to lose if a shop is found in violation of the emissions laws and regulations.

While the switch over from using an exhaust gas analyzer to just relying upon what the car's DME can provide regarding emssions related info (which is considerable I might add) has taken place -- both of my cars have not had the exhaust gas analyzer check now for a while -- both cars get a pretty careful check for any signs of non-factory exhaust systems.

It is not only the CA smog laws that one might be in violation of -- though that is a concern -- there are federal laws that make it a crime for even a vehicle owner to modify his car's emissions systems using parts/hardware that are not certified by the EPA/CARB as emissions compliant.

Thus I am rather amazed that you would advise a CA car owner to break state and federal laws and on a public forum no less.

 

You're probably right in that the cat is likely to have less impact than a muffler, but given that the catalytic converter still flows air, it should impact the exhaust sound in theory.

Those are definitely valid and thoughtful concerns. Regarding legality / smog checkability, I would expect something that's CARB-approved to negatively impact neither, but if others have experiences to the contrary, I'd love to hear about them.

 

Actually I said "You must buy OEM new parts for your car to one bazzilion dollars. "

For opinion I think it is ridiculous that you aren't supposed to be able to install used OEM cats.

I have seen OB2 approved (CARB unapproved) aftermarket cats pass CA SMOG on the old rolling road machines with gas analyzer. The company likely didn't pay the shake-down CA fee to get CARB cert. So if the goal was air cleanliness, that was reached.

FYI The only aftermarket cats that won't end up giving you a SEL are Cargraphic so stick with OEM.