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Mya X Ferron

New Header VS. Emissions?

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Hello lovely people! 

Since meeting some of you at Donnington,  Kuro is no longer completely stock (yay!) - we've been slowly but surely making plans for changing things up performance wise.  Looking to change to a UEL header in the new year (sound preference really as fickle as it may seem) in preparation for a tune and have already changed to a resonated catback in anticipation of this (and will be doing the overpipe and front pipe also). 

My question is; what have people's experiences been like with a decat header and/or high flow 2nd cat when it comes to emissions and MOT type stuff? This is our first modded car so we're pretty fresh and don't want to screw ourselves over 😂 any advice will be sincerely welcomed. 

Thanks a lot in advance and apologies for being dense! 

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3 minutes ago, Mike@TD.co.uk said:

Leave the genuine second CAT in place is what we recommend. Many many people do this and the cars sail through an emissions test.

 

Thanks

 

Mike

Cool perfect, was worried only having 1 cat would cause issues. Thanks for the peace of mind :)

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Hmm, been thinking about this a little more and feel like keeping the OEM front pipe,  when the rest of the exhaust system is after market and composed of better materials, would be a bad idea. It doesn't seem very future proof either in terms of future mods (FI specifically). 

Is there a solution for this, when having a de-CAT header? I know many people keep the 2nd CAT but can you have a high flow sports CAT on the front pipe and still make it through the emissions test? 

How are people dealing with this? Surely some of you have changed the entire exhaust system including OEM 2nd CAT? 

Apologies for reviving old post just getting closer to modifying and want to be certain. 

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Hi Mya,

Generally speaking, from my experience, a high flow cat (for example the Berk) will get you through emissions IF you have a good-quality "backbox" style catback exhaust. I got through my 2016 MOT with a Tomei UEL, Tomei OP, Berk HFC and an Invidia Q300, and they said it was fine. This year however the HFC has deteriorated and I JUST got through the emissions test, and that was with the stock catback rather than the Q300 which is one of the higher quality exhausts. As a caveat to that, I did spend the best past of 18 months blowing flames out of the exhaust and therefore probably burnt the thing to a crisp (no regrets!).

So it can be a bit hit and miss with the cheaper HFC pipes if you have a Y style catback, or just if you get unlucky.

A high quality HFC pipe like an Invidia, OR a higher-capacity HCF like the Cobra may be a better bet for futureproofing but will cost you more and still limit power in the long term. Alternatively, go full decat and find a friendly MOT tester (I believe Mike @ TD has a local one that he points his turbo customers to ;) ) who will fudge the emissions test for you.

A better alternative, and one that many people use, is go full catless for the max power, and simply swap the stock pipe over for MOT time. only 4 bolts and 2 gaskets and doesn't take long.

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2 hours ago, Paul said:

Generally speaking, from my experience, a high flow cat (for example the Berk) will get you through emissions IF you have a good-quality "backbox" style catback exhaust.

Alternatively, go full decat and find a friendly MOT tester (I believe Mike @ TD has a local one that he points his turbo customers to ;) ) who will fudge the emissions test for you.

Why would a cat-back make any difference? It has nothing to do with emissions.

Also aprobably not best to post that about a vendor on a public forum....

A HFC will work fine IF the quality of the cat is good. The issue is that decent quality catalytic converters cost a lot of money. Look at the one that H&S offer, it's £600. That would certainly pass an MOT year after year, was designed to keep road legal if removing running a non-catted manifold. Cobra now make one that should work no issues, speak to @Mark@Abbey M/S about one of those. The Berk one is from the USA and no doubt uses a cheaper ceramic brick hence that's why it is much cheaper. 

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Just to add, make sure you get a resonated system if you're going catless to quieten it a bit. I've done this with a full TD manifold, decat pipe and resonated system and it's fine. Not massively quiet of course, but no problem with noise limits on the track which is the measure of whether it's okay or not. :) 

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1 hour ago, Lauren said:

Just to add, make sure you get a resonated system if you're going catless to quieten it a bit. I've done this with a full TD manifold, decat pipe and resonated system and it's fine. Not massively quiet of course, but no problem with noise limits on the track which is the measure of whether it's okay or not. :) 

Already got a resonated cat back, not to worry. Had it since summer 😁

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1 minute ago, Lauren said:

Cool. Which one? 

Just had one made up by a local exhaust shop in Birmingham. It's only 2.5" though so probably not going to stay on there for more than a couple of years (if we go FI). 

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