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      08-06-2011, 02:35 PM   #1
Len_Beach
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Replacing primary cats with secondaries to avoid CEL?

I'mlooking to mod an OEM X-Pipe and have read that removing the primaries gives the biggest gain.

I still need cats to pass a UK MOT emissions test.

Would it be possible to cut the secondary cats out and replace with straight pipe then reinstall the secondaries in place of the primaries?

Would this still pass an emissions test and not throw a CEL?
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      08-06-2011, 03:05 PM   #2
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Interesting. Not sure of the answer would think this may work but wanna hear from others.
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      08-06-2011, 05:59 PM   #3
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You could just replace the primaries with straight pipes and re-install for emissions. The way you are talking about sounds like more work than necessary.
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      08-06-2011, 07:03 PM   #4
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what real sense?
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      08-06-2011, 07:18 PM   #5
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Ehh what?
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      08-06-2011, 07:19 PM   #6
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just spend the money on a tune after you delete your primary cats.
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      08-06-2011, 07:58 PM   #7
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Yep that's my plan as well challenge and evolve. Cel on now and waiting on tune to arrive.
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      08-07-2011, 07:25 AM   #8
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I'll be using the Evolve-R so I'm sure Sal and the boys can accommodate the cat mods.

I want to use the secondaries in
place if the primaries as I don't want to be in a position where I have to swap pipes each year.

My understanding us that the secondaries are 200 cell? Will these provide enough filtration?
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      08-07-2011, 09:54 AM   #9
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Quote:
Originally Posted by Len_Beach View Post

Would it be possible to cut the secondary cats out and replace with straight pipe then reinstall the secondaries in place of the primaries?
No. The secondaries are larger than the primaries in diameter. The stock primaries are semi flat for clearance reasons. If you were to fit the secondaries there, they would hang down considerably. Which is why all aftermarket X-pipes do not have resonators or cats in that location.
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      08-08-2011, 09:43 AM   #10
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Quote:
Originally Posted by saeedg48 View Post
just spend the money on a tune after you delete your primary cats.
That will only get rid of 1 of his problems. Depending on how stringent the emission testing is over there will determine if using secondary cats is enough.

The easiest way is to use a bolt on X pipe to switch quickly (it can be used WITH a O2 delete tune as the primary cats and oxygen sensors will be functioning) or extend the rear O2 sensors but like said the secondary cats may not be enough.
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      08-08-2011, 04:44 PM   #11
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Quote:
Originally Posted by Len_Beach View Post
I'mlooking to mod an OEM X-Pipe and have read that removing the primaries gives the biggest gain.

I still need cats to pass a UK MOT emissions test.

Would it be possible to cut the secondary cats out and replace with straight pipe then reinstall the secondaries in place of the primaries?

Would this still pass an emissions test and not throw a CEL?
What you will be doing is essentially having a HFC Xpipe (like one from Gintani or AA)

It'll be easier for you to buy one of those than to modify you stock one the way you want to do it
you'll have clearance issues putting the stock 200 CELL cats in the front
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