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Two Cats?

Discussion in 'Chevy Silverado Forum (GMC Sierra)' started by Metaluzc, May 9, 2011.

  1. Metaluzc

    Metaluzc New Member

    Just wondering if the '03 2500HD trucks came with two catalytic converters standard? From the pictures I have taken, it appears that my truck has two cats and I thought that was usually only needed for a true dual set-up. They were on the truck before I bought it, so I'm just trying to see if the prior owner did some modification or if it rolled out of the factory this way. Also, since I don't have true duals now, are two cats overkill?


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  2. dsfloyd

    dsfloyd New Member 1000 Posts

    yep one on each pipe before you get to the muffler.
  3. silveradotrailblazer

    silveradotrailblazer New Member 1000 Posts

    Alot of people cut off the "Y" pipe behind the cats and run true duals. There is no performance gain with this mod unless your putting out over 500hp. Most people do it for looks.
  4. Metaluzc

    Metaluzc New Member

    That must be what happened then because there is no y pipe at all.
  5. silveradotrailblazer

    silveradotrailblazer New Member 1000 Posts

    Exhaust from 4cylinders with flow through a cat quicker than 8cylinder into 1 cat. Hope I explained that right.
  6. Metaluzc

    Metaluzc New Member

    Basically two cats on an 8cylinder truck has better air flow than one cat on an 8cylinder truck?
  7. KyleZ71

    KyleZ71 New Member

    "Exhaust from 4cylinders with flow through a cat quicker than 8cylinder into 1 cat. Hope I explained that right."
    Wow that make alot of sense, I always wondered why mine came with two cats, as well as my father's Tahoe.
  8. clgoch187

    clgoch187 New Member

    the 2500 hds run 2 pipes back to the muffler so no 2 cats is not over kill and they a re high flow cats, so they stock exhaust system allthough quiet is pretty good performance wise

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