I live in the DFW area, and in major metropolitan cities in Texas vehicles must undergo and past emissions testing as part of the annual state inspection process. Testing facilities (which are licensed but not operated by the state) use an exhaust probe on older vehicles and connect directly to the OBD port on vehicles so equipped to check emissions.

My ’03 996 turbo currently has an FVD flash and stock exhaust, and passes emissions with no problems. However, I’m considering adding an aftermarket exhaust but have some concerns with getting the car to pass emissions. Most folks I have talked to say that an aftermarket exhaust with quality 200 cell cats will still pass emissions with no problems. However, I have been told by a few folks that exhausts with 100 cell cats may or may not pass emissions, and that the absence of a check engine light (assuming it was a result of an O2 sensor reading) does not mean that the car will still pass emissions. The last thing I want to do is swap back to the OEM exhaust every year just for inspection purposes.

Not looking to rehash any previous threads on what specific brand of aftermarket is best. Just looking for any info anyone may be able to offer in regards to CAT cell size and or quality, and emissions testing.

Thanks for your input.

 

I'm running Europipe with 100 cell cats and had no problem with Calif smog test which is about the most stringent and chicken**** process in the nation. I can go along with the emissions part, but the so-called "visual inspection" can flunk you even if your're running cleaner than minimum specs. If you can pass in California, you should be able to pass anywhere.

 

100 Cell shouldn't be a problem in TX. All the O2 sensors are still in place and functional. Don't disconnect the battery for any reason right before an inspection. Your readiness codes will not set properly. Have an oil change at your emissions station and pal around with the personnel. There will probably be no visual.

 

if you get a CEL from your cats/02 sensor, you can always have one of the better tuners custom tune your software to ignore the 02 sensors so you don't get any CELs
just an option. i had Protomotive do that for my VF Supercharger system and gt3 cats

 

You should be fine...for an OBD2 car, they plug in this computer that checks like 8 parameters to make sure all of them are working properly...if they are, and no CEL, the car passes.

 

Would ignoring all 4 O2 sensors not create any problems with ECU evaluation for A/Fand other parameters?

 

I'm also running a Europipe with 100 CEL cats. No issues in Metropolitan Atlanta.

 

I think he means have the tuner raise the tolerances on the post-cat o2s.

 

i am not sure. Todd and Paul at proto did it for me. I think they only modified the software to ignore the two O2 sensors after the cats

 

probably!

 

maybe

 

Could be or not necessarily.

I understand what you're saying about the aft sensors.

 

To my knowledge, there is NO 996tt exhaust that is 'california legal' since none are registered with CARB. Most pass, however, since smog shops rarely see 996TTs and don't know what they are looking at- and the emissions values are fine.

Have an emissions test done at a porsche dealership in CA and see if it passes.... (I know, what dumbs--- would do that...)

Feel like a broken record, but when people talk about CA smog it is important to explain what 'legal' is and what 'pass' is...

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