dual catalyic converters legal ?

Discussion in 'High Performance Modifications' started by fnoblitt, Jan 12, 2022.

  1. fnoblitt

    fnoblitt Veteran Member

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    i have a set of smog legal headers for my 79 camaro. i'd like to make it a real dual exhaust. and add a cat to the left side (already have one on the right side). would this be legal in california ? or am i forced to cram it all into 1 cat, then into duals like a stock z28 ?
     
  2. BonzoHansen

    BonzoHansen Administrator Lifetime Gold Member

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    Probably not as it modifies the factory smog setup. I'm sure the California guys will come in.
     
  3. Knuckle Dragger

    Knuckle Dragger Mayor of Simpleton Staff Member Lifetime Gold Member

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    Absolutely not. Sucks but that's the rules on it (Did smog in Cali for years)
     
  4. Lowend

    Lowend Administrator. .a car, a man, a maraca. Staff Member Lifetime Gold Member

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    ^THIS
    CA Smog law is frustrating in its lack of common sense at times. They don't even test tailpipe emissions most of the time anymore.

    That said, there is no magic in dual cats, and modern high-flow cats really aren't a major restriction. I have seen cars make well over 450 Horsepower through a single 3" Cat many times.
     
  5. fnoblitt

    fnoblitt Veteran Member

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    oh well, guess i'll have the stock system for smog time, and fab up a custom bolt on dual system for the other 1 yr and 11 months.
     
    Rosster likes this.
  6. Lowend

    Lowend Administrator. .a car, a man, a maraca. Staff Member Lifetime Gold Member

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    It is (or was) legal to have a "test pipe" which could mean a y-pipe with a block off plate
     
  7. 1980RS

    1980RS Veteran Member

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    Best single cat setup is the ones GM used on the 4th gen LS1 cars, my buddy swapped his manifolds out for Kooks headers, and dual race cats that would at the time pass smog laws. After it was tuned for the new exhaust it only picked up 14hp, so the factory setup is pretty good sometimes. Just keep what you have and dump the pancake converter and get a good monolith converter, it will be a lot better.
     
  8. Rosster

    Rosster Veteran Member Gold Member

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    California has gotten so anal the cats also have to have the proper stamp on them if a replacement cat and mfg after a certian date (dec 2017 iirc) or they fail it on inspection even of it would pass a tail pipe test. Also if it doesn’t look completely stock, they will fail it on visual inspection. Back in the day you could get someone to smog it without ever having to have the car. Now the nazis running calif make it so the the test system can’t be easily defeated and the fines if caught are astronomical. They also have roving “customers” going to random smog shops to see if they are following the law or doing something illegal.
     
    Last edited: Jan 14, 2022
  9. muscl car

    muscl car Veteran Member Lifetime Gold Member

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  10. Knuckle Dragger

    Knuckle Dragger Mayor of Simpleton Staff Member Lifetime Gold Member

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    And that's exactly why the techs have no leeway anymore. If it wasn't abused the program would still allow the tech to make a judgement call on whether or not it effected emissions.
     

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