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The mkiv Supra Owners Club

Why do people de-cat


jackso11

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That is not correct.

Every MOT tester I have asked in the last 2 weeks....and I have asked a lot! say it goes on engine number not car model, so if its a 2JZ-GTE there is an exact match and it needs a cat to pass. If it is an NA it will be a 2JZ-GT, no match, so it will pass.

 

I am sure there will be MOT testers backing me up on this very shortly

 

If you check out notes 5 and 6 it mentions that it must match the engine code AND the Vin number.... which it won't.

 

Makes no odds to me as my car is a 1996 though :(

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If you check out notes 5 and 6 it mentions that it must match the engine code AND the Vin number.... which it won't.

 

Makes no odds to me as my car is a 1996 though :(

 

If that is true then my car should get through with no problems as its a 1994. Can any MOT tester on here confirm if that is the case?

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n/a's will benefit from a decat. From what I understand they get very loud too, louder than TTs do. Not sure why that is though.

 

Yes N/A will benefit depending on its configuration and type of exhaust,but its a very small gain maybe 3-10BHP, the reason they are louder, is because they don't have a turbine in the exhaust flow to dampen the exhaust note.

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I had a high flow cat fitted last year when I made the move to BPU. The cat itself cost about £220 IIRC - it was fitted by a garage who used the same one on their race car when they introduced restrictions in the series they raced in. That was a 700bhp+ Evo.

 

My cat is fitted in the middle of a custom second decat pipe.

 

I still need a restrictor ring as I was overboosting to around 1.35bar when it was first fitted without one.

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I guess you can fit them and still increase power, but fitting a sports cat will result in reduced power compared to if there was no cat at all.

 

If you run 1.2 bar boost with a double decat would the power still be the same as 1.2 bar boost with a sports cat? or would it knock of bhp even though you are running up to the same boost?

 

 

I don't understand why some people seem to be able to get their car through with no cats (TT) and others don't. How can some testers do the no cat test and others say cats are needed?

Edited by jackso11 (see edit history)
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I guess you can fit them and still increase power, but fitting a sports cat will result in reduced power compared to if there was no cat at all.

 

If you run 1.2 bar boost with a double decat would the power still be the same as 1.2 bar boost with a sports cat? or would it knock of bhp even though you are running up to the same boost?

 

 

I don't understand why some people seem to be able to get their car through with no cats (TT) and others don't. How can some testers do the no cat test and others say cats are needed?

 

You will lose power if you stick a restriction in the exhaust, compared to unrestricted.

And as for pass/no pass, any modern well maitained injection engine should have no probs passing an MOT. A Soarer I used to own passed with no cats and a smoking turbo lol

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To be fair on my 'friendly' MOT testing station, I do always take my second cat pipe to the garage, so if they need to swap it over for the test, then it's all above board on the day, and I take the risk from there on.

 

I wouldn't want any garage losing their licence for taking those sorts of risks.

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To be fair on my 'friendly' MOT testing station, I do always take my second cat pipe to the garage, so if they need to swap it over for the test, then it's all above board on the day, and I take the risk from there on.

 

I wouldn't want any garage losing their licence for taking those sorts of risks.

 

the risks are if the vosa people are parked around the corner with there laptops and then pop there heads in once the mot test is logged off, they will then re-test the vehice. if we pass and its a fail then bye bye license and our bread and butter.

 

best thing to do is pay extra and get the cat on for test then remove the cat, puts testers minds at rest and we can put our hands on heart at the end of the day..

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the risks are if the vosa people are parked around the corner with there laptops and then pop there heads in once the mot test is logged off, they will then re-test the vehice. if we pass and its a fail then bye bye license and our bread and butter.

 

best thing to do is pay extra and get the cat on for test then remove the cat, puts testers minds at rest and we can put our hands on heart at the end of the day..

 

I have said this, but so far it's been declined, so they are taking the risks when they don't actually have to. I hope they know what they are doing!

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I have said this, but so far it's been declined, so they are taking the risks when they don't actually have to. I hope they know what they are doing!

 

i would warn them mate, we had a similar case on a bike the other week but had a slap on the hand as they thought the number plate size was too small, but we argued it was suitable for its off road use and letting was clearly sized correct.

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Jackso, just put the second cat back on the the test and the next day remove it. That way everyone's covered and you get your ticket for another year. If you get pulled for a VOSA roadside check and fail the emissions because you have taken it off, most likely you will get a ticket giving you X amount of days to get it sorted, but I think the odds of this happening are slight. If you need a cat (either) to get it through then let me know and I can lend you one.

 

no, I wouldn't want anyone losing a licence. Just asking if a pre 1995 car can do the no cat test or not.

 

I want to have a car that can pass a normal MOT but don't really want a cat, hiflow or not.

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