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P0420 - Need New Cats

Discussion in 'General Chevy & GM Tech Questions' started by KyleZ71, Feb 11, 2013.

  1. KyleZ71

    KyleZ71 Rockstar 4 Years 500 Posts ROTM Winner

    Had the stupid P0420 code for some time now, but I've always been able to shake it... until recently. Knowing that there could be many causes I stopped by Monro Muffler and had them hook it up to their computer. Told I need new cats... When asked how much they charge for one they said they replace the whole y pipe and that runs $975 :grrrrrr: (summit sell the whole y pipe units for around 470). I know cats can be cut out and welded in (even though they said they can not) what would you all recommend? New cats or the whole y pipe unit itself? Since they need replaced I was thinking of just going with magnaflow or flowmaster highflow replacemets. Thanks all!
  2. kinson33

    kinson33 Member 1 Year 100 Posts

    I bought the Magnaflow y-pipe with the high flow cats. Easier IMO to just do that than pay $100 per cat and pay someone extra to weld them in. Just Bolt the new pipe in yourself...

    I'm running that y-pipe with no muffler on my 5.3, just a resonated tip and it sounds SWEET. Not obnoxious; nice, deep, smooth tone.

    I think I paid a little over $425 for mine through advanced auto. Ordered online and picked up at the store, they have discounts all the time.
  3. TRPLXL2

    TRPLXL2 Epic Member 5+ Years 1000 Posts Platinum Contributor

    Summit Racing has the Magnaflow High flow cats for $60.97 each, that is there normal price as I just bought 2 of them. You would just have to have someone weld them in, only thing I would recommend is remove the 02 sensors BEFORE welding or you'll be replacing them as well.
  4. Conlan Rose

    Conlan Rose Active Member 2 Years 1000 Posts

    I did this research for my truck because my pass side converter is dead and keeps throwing a p0430 code. It is actually cheaper in the long run to just replace the y pipe and converters then buy them individually. I was looking at both Magnaflow and Flowmaster which are both about the same price, But you will need new O2 sensors. Actually either way you may need new ones because a bad cat can kill them.
  5. dpeter

    dpeter Rockstar 4 Years 500 Posts

    Whatever way you go, be sure to keep the old cats. and take them to a salvage yard (scrap metal) to sell them and recoup some of your money
  6. kinson33

    kinson33 Member 1 Year 100 Posts

    Cheaper, maybe... Easier, definitely.

    Plus it just sounds great. when you combo it with a straight through muffler or none at all!

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