Hello all,

I live in the lovely state of California where emissions checks are a necessity to register my 996TT. I am currently in the market for a new exhaust system and was wondering if a 100 cell cats will be enough to pass Cali Smog Checks. Will 200 cells be enough? Is there much of a performance advantage going 100 vs. 200?

Thanks!
Chuck~

 

My understanding is that 100 cells give frequent CELs. I doubt 100 cell cats would pass Peoples Republic of Cali air test but have no hard data to back it up.
I went with 200 cell cats to avoid CELs but dont know if they would pass an air test...

 

power is somewhat diff from what i know. Hey your asking someone who has str8 pipes, and live in ca!

 

There are actually threads that you can search up that dicusses this in detail.

 

hi guys i am newbie in this.



can i go to muffler shop to do this custom mod on stock cats?

also usin stock exhaust, what wud noise improvement be?

 

and not found any relevant threads with regards to CA smog testing and 100 cell cats.

FYI I have 100 cell cats and after 2 years no CEL's or other problems - but this time next year I'll need to smog test my TT and am thus interested in other peoples experiences.

Some posters say it 'should pass ok', but I've not been able to find anyone who has 100 cell cats and has passed CA smog and if so by what margin.

 

One good thing about our cars being awd in CA is we don't have to go through the standard rolling dyno test. They just check for computer codes and do the sniffer test at idle and 3500rpm I believe? Either way its much easier to get by then a rolling test.

 

This is true. I just smogged my car with the existing exhaust. They just plugged a cable into the OBDII port and put a probe in the tailpipe. No roller dyno due to it being AWD. The tech said it passed and gave me a printout all within 15 minutes.

 

WRONG. The car will pass smog with 100 cell just fine. It's amazing how much misinformation is out there.

 

And your helping to spread it

When new and clean, 100 cell cats are fine. However, as they age, it gets easier to plug causing CELs to come on since the flow to the downstrean sensor starts to be inconsistant.

This happened to me last year (not in Ca, in Tx they just do an OBD2 test). I had been getting CELs and it failed the test. So I had to get them re-cored.

There's nothing wrong with 100 cell cats.....they just have a shorter life span.

 

There is no aftermarket exhaust that is fully "california legal".

They may pass the tailpipe test, but do not tell the inspector it is afetrmarket. No company has a CARB listed and certified exhaust.

Just FYI, since we are talking 'misinformation'...

A

 

Agreed. I had 100 cell cats and had CEL. I had 200 cell cats and had CEL also. Think of 200cell cats as race cats, more flow.

 

Thanks for all the replies.

Would one burn gases cleaner than the other?

 

If the manufacturer buys good cats like the ones from Europipe you will never have cell's and they also use 100 cell cats..But they are expensive cats..

 

I have a fabspeed loud on my car, I'm not sure if the catalytic converters are 100 cell or 200 cell. I will tell you that two years ago I smogged the car and it passed, but we did have to get the cats really heated up in order to do so...I just got the dmv paperwork in the mail letting me know I need to smog it again so I will let you know how it goes. My car is completely original except for the exhaust.