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Hi-Flow Cats and CEL's?

mm2015

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I've been out of the 'modding' world for a couple years, so I am a bit rusty. If I get a set of long tube headers w/ factory connect hi-flow catalytic converters, will they throw a CEL? If they do throw a CEL, is there a way around it?

I am looking at doing a "custom" exhaust with long tubes w/ hi-flow cats, a borla resonator (replacing stock one), and borla axle backs. I understand I will dampen the flow a bit with the borla resonator, that's simply because I do not want the car to be overly loud, as it's my daily daily driver. Anyone see any issue with doing an exhaust like this? I saw the thread with the Long tube headers and stock catback, but I want to get rid of those tiny exhaust tips and the heavy resonator.
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gsxr1300

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Jmeo and I have Kooks headers with their green cats and we both have no CEL.
 

Grimace427

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I've been out of the 'modding' world for a couple years, so I am a bit rusty. If I get a set of long tube headers w/ factory connect hi-flow catalytic converters, will they throw a CEL? If they do throw a CEL, is there a way around it?
99% of the time yes you will get a CEL when you remove the stock cats. You can add O2 sensor non-foulers to trick them to running like normal.

Jmeo and I have Kooks headers with their green cats and we both have no CEL.

You also have a tune. Can you verify your readiness tests are all active?
 

gsxr1300

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Yes I left one unplugged and got a CEL
 
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mm2015

mm2015

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So if I went with Kooks and green cats (with no tune) would I throw a CEL? If I have to get a tune, I'd rather wait until I can put one of the coming intake manifolds on as well.
 

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gsxr1300

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Whipple tune doesn't turn off any sensors, StangDan has Stainless Power headers with high flow cats with the Whipple tune and got a CEL untill he installed spacers.
 
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marylandspeed

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Give us a call on the Kooks with green cats. They don't throw code and are about the best performing aftermarket cats out there! We are Kooks largest dealer and can really hook you up!
 
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mm2015

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So realistically, only the kooks with green cats are NOT going to give me a CEL?
 

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2015 Silver GT

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So realistically, only the kooks with green cats are NOT going to give me a CEL?
Yes and even those have been known to trip a CEL. And those Kooks cats are stupid expensive. You really should get a tune with it since you will also need to turn off the COT.
 

Jeff_oddo

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Give us a call on the Kooks with green cats. They don't throw code and are about the best performing aftermarket cats out there! We are Kooks largest dealer and can really hook you up!
My car just threw a code today with my Kooks green cats I installed a few weeks back. P0420 "catalyst system efficiency below threshold"
 

Bartly

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My car just threw a code today with my Kooks green cats I installed a few weeks back. P0420 "catalyst system efficiency below threshold"
But, but, but didn't I just hear a vendor say that wouldn't happen? Uhhh, does not compute......
 

Jeff_oddo

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I have emissions in NC, so I cannot just turn the rear O2's off. They won't allow the readiness monitors to set to pass. I guess I'll look into the defoulers.
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