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Cats? Remove Or Keep


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#1 kxdan01

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Posted 18 August 2011 - 07:33 PM

Hey guys is there any advantage to removing my cats, i want the truck to be louder, now i have 2 Flowmaster 40"s welded in place of the stock Dual IN/OUT muffler exiting through the stock tailpipe and tip and it sounds great but i want it a little louder(though i may regret it later but f*** it) so i was thinking about removing the cats and putting straight pipe in their place, ill have a Wheatley 93 Tune to adress CEL and any LIGHT/MIL issues, and im not worried about emmisions or if its illegall or not, will i feel any power or notice any difference at all, good or bad, will it affect fuel economy or power in any way and will it really make it that much louder? Thanks guys and please help me out here, by the way im new here and look forward to sticking around a while, i ditched my Cobra and F150 and got a low mileage immaculate Silverado SS AWD in the Arrival Blue Color a few months ago and im so glad i did, what a cool truck!!!
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#2 Guest_jasonhensley22_*

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Posted 18 August 2011 - 10:14 PM

If you don't have to pass emissions, delete them. If you have to pass, install hi-flows. Best rule of thumb for this "Better flow = more hp" so cats will quiet it down a bit but rob a little bit of power, but not much, like probably 5-10 hp...
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#3 Mr. P.

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Posted 19 August 2011 - 10:04 AM

Removing the cats will not gain very much, on a supercharged truck it will gain about 1+ tenths in the 1/4-m. It will make a definite difference in the exhaust, not very much louder but raspier. If you run forced induction, nitrous, or high octane fuel they must be removed or you risk melting them down; on N/A vehicles I would encourage you leave them on for legal reasons, especially if you ever resell the truck the new owner can force you to have to reinstall them (and any other emissions equipment) as a condition of sale. So if you really want to remove them, what I would do is to unbolt the factory Y-pipe and replace with a catless Y-pipe, that way for inspection or resale you can easily return the truck to original condition.

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#4 ThatTallCanadian

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Posted 19 August 2011 - 11:23 AM

It'll probably sound like shit tbh if you're running flowmaster 40's
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#5 The_aSSet

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Posted 19 August 2011 - 12:26 PM

It'll stink too lol
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#6 Sssz28

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Posted 13 March 2017 - 12:33 AM

It doesnt throw a cel for removing them??? I'm about to do headers but one studs already broke and it's gonna take more time than I have currently. But I want some better sound/mpg. You anyone know who they sound cat-less with stock muffler?
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#7 SS-GTP

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Posted 13 March 2017 - 09:15 AM

Yes, you will get CEL for P0420 & P0430 - loss of catalyst efficiency in banks 1 & 2.  I'm running no cats on a magnaflow muffler and above about 1/2 throttle it gets poppy/raspy.  I'm considering installing high-flow cats to see if it will reduce that.


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#8 Sssz28

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Posted 20 March 2017 - 06:31 AM

A simple tune out will correct those codes. But the mpg gain and power is the only reason Im gonna LT my new work truck.
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#9 cleansss20

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Posted 20 March 2017 - 11:51 AM

I had lt headers, no cats and magnaflows on my truck and it sounded horrible. Drone and popping. I had to add in some resonators and x pipe and it sounds better. But unless you need to remove the cats I wouldn't.


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