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LS2 Headers Question

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Old Apr 1, 2015 | 04:06 PM
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Hello all,
I have been following this forum for a long time and found most of the answers I need. I have an '05 corvette z51 with Borla cat back exhaust and I'm ready for some headers. I want to put on the LG street series headers but I have a question about what I need. A friend of mine says that I should get high flow cats with it instead of no cats because the LS series engines needs the back pressure provided by the cats. Can anyone provide help in answering if this claim is true or not?
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Old Apr 1, 2015 | 04:16 PM
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No cats will give you 5-10hp more but will also give you more exhaust smell.. I run no cats, and the smells is not bad at all .. The statement about back pressure, I have never heard of it maybe he is thinking of motorcycle exhaust.
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Old Apr 1, 2015 | 04:57 PM
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Back pressure is not an issue on these engines. You can run it with or without Cats.
I chose headers with high flow cats as the restriction is minimal and only near redline. The high flow cats reduce the fuel smell inside the car at stop lights.
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Old Apr 1, 2015 | 05:35 PM
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I dont run cats, inside the car ive never smelled anything.
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Old Apr 1, 2015 | 06:40 PM
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Originally Posted by DRJONES1227
Hello all,
I have been following this forum for a long time and found most of the answers I need. I have an '05 corvette z51 with Borla cat back exhaust and I'm ready for some headers. I want to put on the LG street series headers but I have a question about what I need. A friend of mine says that I should get high flow cats with it instead of no cats because the LS series engines needs the back pressure provided by the cats. Can anyone provide help in answering if this claim is true or not?
Hello,

Alittle backpressure at low RPMs helps you and then hurts you at high RPMs. No backpressure hurts you at low RPM and helps you at the high RPMs.

If you get caught without catalytic converters the fine can be up to $2500. That's an expensive way to gain less than 5hp.

Good Luck,

Douglas in Green Bay
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Old Apr 1, 2015 | 09:35 PM
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I would get cats. I'm running without them now and there is a smell in certain situations.. not worth not running them if you can
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Old Apr 1, 2015 | 10:39 PM
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Thank you all for the quick responses. Seems as though I have some decisions to make.
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Old Apr 2, 2015 | 07:26 AM
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Originally Posted by DRJONES1227
Thank you all for the quick responses. Seems as though I have some decisions to make.
yes you do. pay for cats now or pay more to have them added later.
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Old Apr 2, 2015 | 02:29 PM
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I passed emissions last week, and I dont have cats. LOL Thanks to my tuner.
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Old Apr 2, 2015 | 07:24 PM
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Originally Posted by Kolk1
I passed emissions last week, and I dont have cats. LOL Thanks to my tuner.
Easy enough.
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Old Apr 3, 2015 | 06:21 PM
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Don't fight the horrific odor and get high flow cats. BTW, there is no way the offroad gains 10 hp, it's closer to 3.
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Old Apr 3, 2015 | 09:35 PM
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Get the Cats.. not worth the possible hassle, or the smell IMO
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Old Apr 5, 2015 | 10:12 AM
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I have non catted obx and borla s type 2's, i wanted loud and the hi flow cats would have killed some of the noise. I went back-and-forth about getting cats are not getting cats because I don't want to smell the exhaust, but I got to be honest the smell is not bad at all and I am very happy with what I did
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Old Apr 5, 2015 | 10:14 AM
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Also if you don't want to tell in the car immediately you can always get spark plug nonfilers and drill them out and you won't have any lights from the o2 sensors. I have a 1999 Honda Accord that I did the spark plug non-filer trick on after I gutted the cat to eliminate an issue. 8 months and many miles no check engine light
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Old Apr 5, 2015 | 10:15 AM
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If you dont want to tune the car immediately ***
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Old Apr 5, 2015 | 01:40 PM
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Default LS2 Headers Question

Originally Posted by black.z51.c6
Also if you don't want to tell in the car immediately you can always get spark plug nonfilers and drill them out and you won't have any lights from the o2 sensors. I have a 1999 Honda Accord that I did the spark plug non-filer trick on after I gutted the cat to eliminate an issue. 8 months and many miles no check engine light
I doubt that would work on these but who knows.

Regardless, the code won't hurt anything until it can be tuned out.
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Old Apr 5, 2015 | 02:46 PM
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https://www.corvetteforum.com/forums/c5-tech/3021018-spark-plug-non-foulers-o2-simulators-not-needed.html
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Old Apr 5, 2015 | 02:47 PM
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http://https://www.corvetteforum.com/forums/c5-tech/3021018-spark-plug-non-foulers-o2-simulators-not-needed.html
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Old Apr 5, 2015 | 02:50 PM
  #19  
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If you wanted to go this route you could send me the spark plug non foulers and I'll drill them out on a lathe for you, for nothing more than the return shipping cost
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