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Catalytic Converter Help!

Discussion in 'Performance & Fuel' started by Chad513, Nov 14, 2011.

  1. Chad513

    Chad513 New Member

    So I ordered two magnaflow performance catalytic converters the other day. i went to 2 local muffler shops today and the first one said that I ordered the wrong ones and the second one said that the 06 Silverado has the best performance cats on the market. Soooo I have two questions: Will putting a "pre OBDII" cat in my truck make it run bad or just run codes? and is it true that GM's cat is the most high flow cat available?
    Also, JEGS told me the cat would work on my truck, it didn't say that is was pre OBDII in the catalog. It says that is is OBDII complaint. The box for the cat is pre obdII. It makes me mad that now I have to pay for shipping so I can return them.

    Another question, do high flow cats really do that much because i was thinking about ordering another set for Dynatech but if its not gonna make my truck sound any louder or get any quicker there is no point.

    Thanks,
    Chad.
  2. 99'HEARTBEAT

    99'HEARTBEAT Moderator Staff Member ROTM Winner Platinum Contributor 1000 Posts

    ...
    The Late Model Factory G.M./Chevy Catalytic Converters.......Flow Much Better than Most think they do......unless your Factory G.M./Chevy Catalytic Converter's are going Out/Bad......there's no reason to replace them for aftermarket Cats.......and I have not seen any kind of Dyno Number's showing any big gains with Aftermarket Cats being installed......
    Last edited: Nov 14, 2011
  3. silveradotrailblazer

    silveradotrailblazer New Member ROTM Winner 1000 Posts

    X2 what Mike said.
  4. ippielb

    ippielb Active Member ROTM Winner 1000 Posts

    Replace the plugged cats with High-Flow cats, i convinced my father to do this on his 2000 silverado, and it doesn't downshift nearly as much going on the highway. He said he got a 1-2 mpg increase from going from the plugged to the highflows. Costed him $100 at the muffler shop.
  5. [Cerberus]

    [Cerberus] New Member

    What brands are out there for high flow cats? I am the second owner, and as far as I know the cats on my 04 silverado are up around 100k miles. I don't have any maintenance documentation to prove otherwise.
  6. The Heater

    The Heater Member

    Hi, Chad513:

    Like the first post indicated, it is my opinion that as you get into newer vehicles, which I will define loosely as after 1995, the OEM catalytic converter is going to be increasingly more efficient at allowing pass through at a lower pressure than the predecessors. And aftermarket units made for your vehicle have to comply with specifications that I don't think allow them to do much about what back pressure is created.

    Again like the first post said, and I heartily agree, if your cat is not malfunctioning, don't replace it and don't blame it for any issue you have with "not enough noise". You can remedy that with the right muffler. Personally, I don't want too much noise. Just a nice rumble.

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