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Thread: P0420 - Need New Cats
02-11-2013, 01:29 PM #1
P0420 - Need New Cats
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 (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!Objects in mirror are losing
2003 Chevy Silverado Z71, 5.3L, K&N 57 series, 2.5'' Flowmaster Super 10 series dual exhaust , Corvette Servo, McNew Automotive Dyno tune, SS gauge cluster, Extang Trifecta Tonneau, Pacesetter shorty headers, Goodmark cowl hood, Sony Xplod speakers, Kenwood DDX-470 exhaust tips, 16" Ultra Badlands polished wheels, Pirelli Scorpion ATR .
02-11-2013, 11:43 PM #2
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.
02-12-2013, 07:31 AM #3
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- Jan 2009
- Norwalk, Ohio
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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.2004 Chevy Colorado
LS1 5.7 swap/TBSS rear axle swap
02-12-2013, 01:44 PM #4
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- Dec 2011
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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.
1996 Chevy Tahoe LT 5.7L V8 4X4 205,000+ miles. Built proudly at Janesville Assembly in Janesville, Wisconsin
Basic mods: Lights all over, bunch of electrical work, and a couple cooling mods.
Check out my other mods in My Garage: http://www.gmtruckclub.com/forum/sho...t-Tahoe-4-Door
02-12-2013, 04:39 PM #5
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 money2000 GMC YUKON SLT, 5.3L tow pkg, G80 rear/w 3.73 gear
02-12-2013, 10:01 PM #6
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