Best advise right here.

I just did this recently, cause I didn't pass "this year" on a downpipe with an OBD2 compliant cat retrofitted on, as well as the cat had a hard time passing at idle. This same set up passed 2 years prior. California changed it's laws. If your cat is not listed on the smog techs computers, you won't pass. Cats do wear over time and their effectiveness goes with it.

Do the OEM swap smog it and be done!

 

I'm not naive and I'm not the police. I could give a crap. I just know that threads like this are often not allowed on other forums, when they contain comments like this:

 

there are a few in modesto that dont check visual

 

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