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I was wondering if you have headers with high flow cats, would you pass inspection? I did a search and saw RMON modified his mid- pipes with the stock cats and passed. So wondering if anyone passed with high flowing cats?
 

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I was wondering if you have headers with high flow cats, would you pass inspection? I did a search and saw RMON modified his mid- pipes with the stock cats and passed. So wondering if anyone passed with high flowing cats?
Todd, yes the problem is the high flow cats, you won't pass with those. I'm planing to do what RMON did as well when the time comes for me to pass inspection.
 

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I was wondering if you have headers with high flow cats, would you pass inspection? I did a search and saw RMON modified his mid- pipes with the stock cats and passed. So wondering if anyone passed with high flowing cats?


If you want to do LT headers (a great mod BTW) save yourself money and aggravation and order the off road mid pipe system and use your savings to fabricate removable "stock" cats. The only PCM's that can be "fooled" are the 2006's. Knuckles and I were in touch for over a year and between us tried every combination in the book to get our high flow cats to pass emissions without success. Also I had to eat the cost of my high flow cats because we damaged them removing them so they couldn't be resold. The stock cats are the only ones that pass emissions at present for the newer cars.
 
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If you want to do LT headers (a great mod BTW) save yourself money and aggravation and order the off road mid pipe system and use your savings to fabricate removable "stock" cats. The only PCM's that can be "fooled" are the 2006's. Knuckles and I were in touch for over a year and between us tried every combination in the book to get our high flow cats to pass emissions without success. Also I had to eat the cost of my high flow cats because we damaged them removing them so they couldn't be resold. The stock cats are the only ones that pass emissions at present for the newer cars.
Rich, what year is your Jeep?
I'm thinking of getting the ones with the high flow cats so I can switch them between OEM, high flows or no cats.
The way I see it is run the OEMs when inspection time comes. :)
The high flow cats for every day use, this way the exhaust smell (especially in summer when windows down) doesn't bother your passengers. :rolleyes:
And no cats when hitting the track. :D
You think this doable?
 

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Discussion Starter · #5 ·
Good point Mario..I was thinking OEM for inspection and no cats for driving. You think it will smell that bad?
 

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Good point Mario..I was thinking OEM for inspection and no cats for driving. You think it will smell that bad?
Yeah bro, had a jeep with a 4.0L HO with long tubes, no cat and Flowmaster muffler and it smelled pretty nasty, it hurts your eyes too. It was a wrangler so the whole jeep was open so it was pretty bad.
 

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Discussion Starter · #7 ·
Really, is their a difference in power with cats and no cats?
 

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Rich, what year is your Jeep?
I'm thinking of getting the ones with the high flow cats so I can switch them between OEM, high flows or no cats.
The way I see it is run the OEMs when inspection time comes. :)
The high flow cats for every day use, this way the exhaust smell (especially in summer when windows down) doesn't bother your passengers. :rolleyes:
And no cats when hitting the track. :D
You think this doable?
This is definitely do able. Just more fabrication expense for the extra set of cats. You need to fabricate the "ends" to bolt into the exhaust system. Our stock cats are choked down to 2 1/2" with an inner pressed in pipe. If the inlets and outlets are opened up to the full 3" they flow noticably better than stock. The stockers are 400 cell cats and the high flows I had were 300 cell. I didn't really notice that much of a difference except at WOT. If I were you I'd do the stock cats first. I never dyno'd my set up with just the cats changed but I doubt the difference would be more than 10-15 hp at the most in a NA set up. If you wanted to go to a high flow cat then a 100 cell cat would have the least resistance to flow compared to stock and still make for less exhaust smell (which isn't really bad with our high energy ignitions). Here's a couple pic's of the "ends" fabricated and what our cat's intake sides look like one with the inner 2 1/2 " pipe and one with it removed to show you what I'm talking about.

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This is definitely do able. Just more fabrication expense for the extra set of cats. You need to fabricate the "ends" to bolt into the exhaust system. Our stock cats are choked down to 2 1/2" with an inner pressed in pipe. If the inlets and outlets are opened up to the full 3" they flow noticably better than stock. The stockers are 400 cell cats and the high flows I had were 300 cell. I didn't really notice that much of a difference except at WOT. If I were you I'd do the stock cats first. I never dyno'd my set up with just the cats changed but I doubt the difference would be more than 10-15 hp at the most in a NA set up. If you wanted to go to a high flow cat then a 100 cell cat would have the least resistance to flow compared to stock and still make for less exhaust smell (which isn't really bad with our high energy ignitions). Here's a couple pic's of the "ends" fabricated and what our cat's intake sides look like one with the inner 2 1/2 " pipe and one with it removed to show you what I'm talking about.

View attachment 19422 View attachment 19423 View attachment 19424 View attachment 19425
Thanks bro!
What year is your jeep?
 

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I have the 06 jeep srt8, so I could do the high flow cats and still pass emissions?
Yes get a see of foulers made.for.the rear .o2.sensors..
 

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I heard from Kooks directly at SEMA this year and saw their new "Green" cat midpipes they are making for us which I was assured would solve our problems and throw no codes when emissions testing. Just don't know how long before they are going to be available...
 

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Discussion Starter · #15 ·
I heard from Kooks directly at SEMA this year and saw their new "Green" cat midpipes they are making for us which I was assured would solve our problems and throw no codes when emissions testing. Just don't know how long before they are going to be available...
That would be great!!! I might have to make a call and see when they are coming out.
 

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Discussion Starter · #16 ·
I heard from Kooks directly at SEMA this year and saw their new "Green" cat midpipes they are making for us which I was assured would solve our problems and throw no codes when emissions testing. Just don't know how long before they are going to be available...
If you want to do LT headers (a great mod BTW) save yourself money and aggravation and order the off road mid pipe system and use your savings to fabricate removable "stock" cats. The only PCM's that can be "fooled" are the 2006's. Knuckles and I were in touch for over a year and between us tried every combination in the book to get our high flow cats to pass emissions without success. Also I had to eat the cost of my high flow cats because we damaged them removing them so they couldn't be resold. The stock cats are the only ones that pass emissions at present for the newer cars.
I just read (RMON) message and he said about the pcm being fooled on the 06's. Does this mean only the 06's can get away with high flowing cats? I have an 06 and im confused?
 

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I just read (RMON) message and he said about the pcm being fooled on the 06's. Does this mean only the 06's can get away with high flowing cats? I have an 06 and im confused?
Todd, yes the '06 PCM can be fooled with custom foulers, someone made here a long time ago and I actually bought a set that never got to use. If you'll be going this route I'll give them to you for whatever I paid for them since I can't use them on my '08.
 
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Discussion Starter · #19 ·
Thanks Mario for the ideal of the foulers. I was thinking, would the stock mid pipes bolt onto the headers? If so, save us the trouble of modifying the OEM cats.
 

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Thanks Mario for the ideal of the foulers. I was thinking, would the stock mid pipes bolt onto the headers? If so, save us the trouble of modifying the OEM cats.
No, different mid pipes. You could have whoever does the install take your factory cats and make some midpipes to work. What Mario says is true. I passed using what he mentions in his post.

I have had my Kooks since 07 and had them off to install the new motor and they are still in great shape and if you use the pull the head method for install, they will fit.
 
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