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Exhaust Decat MOT query
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Old 15 Aug 2007, 09:43 AM   #1 (permalink)
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Exhaust Decat MOT query

Guys,

I'm sure you've all been asked this before a million times so do point me to a thread if so, but..

can anyone explain to me how many cats you need in your exhaust piping to pass the MOT ?

I've got the prodrive sports downpipe, the smaller decat section after that and then the standard STI parts afterwards ( think its a longer pipe with a small cat and then the backbox )

I'm basically wondering if i can replace the longer pipe just behind the BB with a decat one and i can still pass the MOT ?? at my last MOT the guy said i was a borderline pass already so I'm kinda expecting to fail but wondered if a remap would bring me back in line afterwards ?

Russ
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Old 15 Aug 2007, 10:19 AM   #2 (permalink)
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Quote:
Originally Posted by stirus View Post
Guys,

I'm sure you've all been asked this before a million times so do point me to a thread if so, but..

can anyone explain to me how many cats you need in your exhaust piping to pass the MOT ?

I've got the prodrive sports downpipe, the smaller decat section after that and then the standard STI parts afterwards ( think its a longer pipe with a small cat and then the backbox )

I'm basically wondering if i can replace the longer pipe just behind the BB with a decat one and i can still pass the MOT ?? at my last MOT the guy said i was a borderline pass already so I'm kinda expecting to fail but wondered if a remap would bring me back in line afterwards ?

Russ
Russ, the longer pipe doesn't have a cat (you have a newage, right?), it has a resonator in it. Removing this will give you a nicer deeper and a bit louder sound. You can also get rid of the 3rd cat as well and still be MOT friendly. Again this will give you a deeper rumble. At the moment I have up cat, down cat still there; 3rd cat has gone, centre section replaced and a Prodrive BB. In the next few weeks I am going to de-cat the uppie and sports cat the down pipe. I have been assured that even this configuration is MOT friendly.

HTH
John
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Old 15 Aug 2007, 07:43 PM   #3 (permalink)
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As above really mate my 3rd cat taken off and resonator bined. from downpipe is all 3". MOT chap said it was one of the best cars hes had for emmisions.
Dont know why yours should be border line
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Old 16 Aug 2007, 04:00 PM   #4 (permalink)
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Cheers guys,

I think your right that its just a silencer in the 3rd part of the exhaust so i'm thinking of swapping that out for a straight through peice for a better rumble... God knows why mine was borderline MOT pass.. maybe the prodrive cat i bought is a bit crap and its closer to a decat because its not working correctly ??

I occasionally get the "Check engine" light pop up if i've had to put normal unleaded in and my laptop always whines about "emissions below something" but clearing this and putting in optimax fixes it all.

Russ
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Old 20 Aug 2007, 07:42 PM   #5 (permalink)
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just fully decat and remap it mate then find a friendly MOT place
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