Author Topic: Is a sport cat legal?  (Read 986 times)

Offline rcrisp11

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Is a sport cat legal?
« on: May 20, 2018, 06:45:27 PM »
So I’m thinking of getting a new Milltek exhaust to help beef up the sound of my car, and as I’m potentially looking at going to Stage 2-3 numbers in the future it seems like a sports cat is the only way to go without making the car completely illegal.

But how legal actually are hi-flow cats? I’ve heard that they can typically pass an MOT, but that you may only get 1 or 2 out of them before having to replace the cat completely.

Is this right? And if so, what do you guys normally do for MOT’s? Swap out the performance cat with the stock one? Or just take the risk that you will still pass regardless?

Any help with this would be much appreciated.
Thanks

Offline colesey

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Re: Is a sport cat legal?p
« Reply #1 on: May 20, 2018, 06:59:07 PM »
Broadly speaking, the thicker the (expensive) precious metal coating is on the cat matrix the longer it should last.  If you look at some of BCS Nige’s posts from a couple of months ago, he gives a detailed explanation about this.

Offline rcrisp11

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Re: Is a sport cat legal?
« Reply #2 on: May 20, 2018, 07:47:49 PM »
You mean this one?

http://www.mk5golfgti.co.uk/forum/index.php/topic,115478.msg1100297.html#msg1100297

So I basically need to look out for a high washcoat level?

Offline GitFlog

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Re: Is a sport cat legal?
« Reply #3 on: May 20, 2018, 08:02:04 PM »
With the new mot standards that have just come in you want to make sure you get a decent one with a good coating (NormallyAluminum Oxide, some rare earth metals and Platinum and Rhodium) you will find that the cheaper ones might get you through the first mot if its soonish after you put it on then the next mot as the coating has worn down could be a fail.

Buy once buy right talk to @Powervalve Nige  he does some good systems and might sort you a discount :wink: hes a nice guy and has supplied so many of the forum members and i have seen nothing but praise about the quality of workmanship, i would more than consider him if your thinking of getting a Milltek.
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Offline GitFlog

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Re: Is a sport cat legal?
« Reply #4 on: May 20, 2018, 08:02:45 PM »
You mean this one?

http://www.mk5golfgti.co.uk/forum/index.php/topic,115478.msg1100297.html#msg1100297

So I basically need to look out for a high washcoat level?

Thats the one
Reflex Silver 2005 Golf GTI (AXX)

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Offline bobby_fodge

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Re: Is a sport cat legal?
« Reply #5 on: May 20, 2018, 08:21:32 PM »
I've got a millek cat back and it sounds very underwhelming

Offline rcrisp11

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Re: Is a sport cat legal?
« Reply #6 on: May 20, 2018, 09:27:09 PM »
With the new mot standards that have just come in you want to make sure you get a decent one with a good coating (NormallyAluminum Oxide, some rare earth metals and Platinum and Rhodium) you will find that the cheaper ones might get you through the first mot if its soonish after you put it on then the next mot as the coating has worn down could be a fail.

Buy once buy right talk to @Powervalve Nige  he does some good systems and might sort you a discount :wink: hes a nice guy and has supplied so many of the forum members and i have seen nothing but praise about the quality of workmanship, i would more than consider him if your thinking of getting a Milltek.

Alright, I’ll get in touch with him as I can’t seem to find any of that information on the website. And @bobby_fodge that’s disappointing to hear. Which type is it? Also, is your car still stock (other than the exhaust obviously)? And have you tried anything else/do you have any other recommendations?

Offline rich83

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Re: Is a sport cat legal?
« Reply #7 on: May 20, 2018, 09:28:48 PM »
Its legal so long as it passes the MOT emissions test.

Offline GitFlog

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Re: Is a sport cat legal?
« Reply #8 on: May 20, 2018, 11:06:07 PM »
what area are you in and are you happy to put it on yourself or do you need somewhere to do it for you?
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Offline rcrisp11

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Re: Is a sport cat legal?
« Reply #9 on: May 21, 2018, 06:11:48 AM »
I’m near London. And myself and a friend will be putting it on once I get round to ordering it. Why do you ask?

Offline bobby_fodge

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Re: Is a sport cat legal?
« Reply #10 on: May 21, 2018, 07:34:21 AM »
I'm not sure what model it is as it was on the car when I bought it. I don't recall seeing a resonator box when I was working under the car.

The car is standard except a panel air filter and gfb dv+. I'm going to hit the pre cat shortly as that's meant to make the exhaust note a bit deeper.

even when revving up to the redline it still doesn't sound sporty.

Offline rcrisp11

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Re: Is a sport cat legal?
« Reply #11 on: May 21, 2018, 10:51:28 AM »
I'm going to hit the pre cat shortly as that's meant to make the exhaust note a bit deeper.

Isn’t that kind of the same as getting a sports cat since you will be removing the pre-cat anyway with this set-up?

Offline bobby_fodge

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Re: Is a sport cat legal?
« Reply #12 on: May 21, 2018, 01:05:38 PM »
Not quite as I'll be leaving the proper cat untouched as I'm not going to go to stage 2. According to the internet gutted the precat is worth doing when I go stage 1 as the EGTs will be lower.

If you get a sports cat you could,

keep your stock downpipe with precat in tact

gut your precat

get a downpipe that doesn't have a precat.

I'm just not after big power, MOT hassle or spending lots on a decent sports cat.


Offline rcrisp11

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Re: Is a sport cat legal?
« Reply #13 on: May 21, 2018, 01:39:58 PM »
Fair enough. Yeah, the Milltek downpipes that I looked at had removed the pre-cat, that’s why I asked. :smiley:

Silly question maybe, but do all stock cars come with a pre-cat fitted? Or was it only for certain model years?

Offline colesey

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Re: Is a sport cat legal?
« Reply #14 on: May 21, 2018, 03:44:50 PM »
Precat is for German emissions testing which has a cold start requirement.