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To cat or not to cat

2555 Views 13 Replies 3 Participants Last post by  MiniSmalls
Hi everyone,
Apologies if this has been asked before but I was struggling for a definitive answer.

I was looking into possibly getting a replacement downpipe for my R56 Cooper S.

Am I right in thinking there are 2 cats in the exhaust system? If so is there 1 in the downpipe and 1 elsewhere?

In other words if I install a decat downpipe will it definitely fail on emissions come MOT time or is there another CAT elsewhere that will keep the emissions down?

Thanks in advance for any advice
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I initially thought 2 ctas, but searching more on this looks like only 1 cat.

Will most likley to fail MOT with decat, next best would be downpipe & high flow sports cat with 100CPI which'll pass MOT.

Both will still require remapping out to stop CEL code.
Hi everyone,
Apologies if this has been asked before but I was struggling for a definitive answer.

I was looking into possibly getting a replacement downpipe for my R56 Cooper S.

Am I right in thinking there are 2 cats in the exhaust system? If so is there 1 in the downpipe and 1 elsewhere?

In other words if I install a decat downpipe will it definitely fail on emissions come MOT time or is there another CAT elsewhere that will keep the emissions down?

Thanks in advance for any advice
the law states the exhaust emissions based parts must all be present and working and tail pipe gasses must be within set limits and 02 sensors must also be working and are tested as part of gas test at mot,
way around it is to cut old cat up and put a straight through pipe with filter part removed or drill out the center of it, then it all looks stock, after this its down to a mapper to get the 02 sensors and what comes out of exhaust to become what the mot gass machine needs to replicate the factory fueling as such, worth speaking to black magic tuning he really good at stand alone maps and removing files from the ecu, as to run catless you will need ecu files altered so dont get limp modes and randow emission fault codes all the time,
Black Magic ECU Remapping Specialist Ltd - Unit 2, 60 Liskeard Road, Callington, Callington - Establishment and car repair
Thanks Mike.

Some really useful info there. I havent decatted a car for a while now. Im used to dealing with jap cars from a few years ago so could get away with different things.
I used to own a GTO twin turbo and had everything removed with a straight through exhaust and that still passed an MOT some how
Did I read in one of your post elsewhere Mike that BlackMagic do a remote service? I ask as Im based in Cumbria so about as far away from them as is possible barring being in another country. Lol
Did I read in one of your post elsewhere Mike that BlackMagic do a remote service? I ask as Im based in Cumbria so about as far away from them as is possible barring being in another country. Lol
yes he does send via UPS is best service they treat the gear nicely, just ring him up ask to speak to john he's really nice guy never talks down to anyone if dont know something etc. he's the guy most of garages around here ask when they have a random fault that they cant work out top bloke. just say mike sent me and off forum mini 2
tell him what you want to do, or ask him whats possible and best way forward, one thing he will deffo say as i will now is this dont put a big map on a prince engine if chain is around 60k old you must do chain every 60k from then on in then they are mental to drive as mini so light, ie check your engine is healthy oil pressure test compression test and no codes stored,
Black Magic ECU Remapping Specialist Ltd - Unit 2, 60 Liskeard Road, Callington, Callington - Establishment and car repair
yes he does send via UPS is best service they treat the gear nicely, just ring him up ask to speak to john he's really nice guy never talks down to anyone if dont know something etc. he's the guy most of garages around here ask when they have a random fault that they cant work out top bloke. just say mike sent me and off forum mini 2
tell him what you want to do, or ask him whats possible and best way forward, one thing he will deffo say as i will now is this dont put a big map on a prince engine if chain is around 60k old you must do chain every 60k from then on in then they are mental to drive as mini so light, ie check your engine is healthy oil pressure test compression test and no codes stored,
Black Magic ECU Remapping Specialist Ltd - Unit 2, 60 Liskeard Road, Callington, Callington - Establishment and car repair
Thanks Mike. I shall have to contact him.

I literally just had a new chain fitted last week and less than 40 miles ago so I'm half way there. Ill get my man with a spanner to do a compression test.

He did seem to think it was a strong engine. Its done a little over 97k on a 2010 car but seems to have been looked after
Thanks Mike. I shall have to contact him.

I literally just had a new chain fitted last week and less than 40 miles ago so I'm half way there. Ill get my man with a spanner to do a compression test.

He did seem to think it was a strong engine. Its done a little over 97k on a 2010 car but seems to have been looked after
he's a good bloke he's where i go when i get one that catches me out as some do i've learnt a bit off him along the way. as we are all always learning. he just got back from a week away at a drag strip they were running a few cars there and one was 350bhp fiat 500 abarth he also does a load of high climb specials for other people, one is a vw golf r32 that the other day on its first day out ran the hill in top 5 and was beaten all day long up this hill ans totally stayed together, when you think when mapping something to it limits and beyond its knowing just how far to push it,
i tend to stick to maps that have a 50/50 effect some more power but better low down low revs torque as this is what gets used most of the time and the mpg lives there as well. and higher mileage cars do better on those types of maps, that said my sons have cooper s mini's both well north of 120k on second chains have oil changes every 8k ish both over 200bhp have been for 4 years now and still go well use a tad of oil but thats how the prince engine rolls, i buy trade 5/30 engine oil off europarts around £40 for 4 gallons ie 20 litres works around £10 per gallon of oil been doing that on all our cars for 30 years or more never had a issue with the oil as good as a branded over priced drum.
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he's a good bloke he's where i go when i get one that catches me out as some do i've learnt a bit off him along the way. as we are all always learning. he just got back from a week away at a drag strip they were running a few cars there and one was 350bhp fiat 500 abarth he also does a load of high climb specials for other people, one is a vw golf r32 that the other day on its first day out ran the hill in top 5 and was beaten all day long up this hill ans totally stayed together, when you think when mapping something to it limits and beyond its knowing just how far to push it,
i tend to stick to maps that have a 50/50 effect some more power but better low down low revs torque as this is what gets used most of the time and the mpg lives there as well. and higher mileage cars do better on those types of maps, that said my sons have cooper s mini's both well north of 120k on second chains have oil changes every 8k ish both over 200bhp have been for 4 years now and still go well use a tad of oil but thats how the prince engine rolls, i buy trade 5/30 engine oil off europarts around £40 for 4 gallons ie 20 litres works around £10 per gallon of oil been doing that on all our cars for 30 years or more never had a issue with the oil as good as a branded over priced drum.
Sounds like the man to know. I'll see what he suggests.

I must admit Im really anal when it comes to oil. I check it a few times a week especially with not having had the car too long. Like to get a feel for what if anything its using. It was odd as I had to top up with a litre a couple of months ago and it hasnt used a drop since so I must have one of the good ones

In your personal experience what would be the best sensible upgrades to do before a remap to get more power but remain driveable on a daily basis? It already spins up the front wheels easily now. Lol. Is a panel filter worth getting? Ive read that induction kits arent very effective on our cars?
its that band of revs from 1200-3000 revs that i believe is best to live with so by increased map to these points transforms them more like a diesel torque that is the best daily use car also helps not to have to change down as much can help mpg as well, you prob find yours as its had chain done makes a big difference to oil use and how offend it gets a does of the red line as well higher revs is more oil use, more wear as well.
induction kits only work when the ecu has had some files removed its funny some so called ecu repair companies say this cannot be done with out the self check finding they are missing and throw up a fault code, black magic has been doing standalone maps on loads of stuff where this is removed for the self check as well , ie on vauxhall 2,0cdti common for the £100 each high pressure glow plugs to fail these are emission item and not really used to start car as such he can pull them no limp modes or lights can same with cat and 02 sensors for track use say, he's got a mercedes c63 amg twin turbo v8 his own car its stupid fast just keeps adding to it.
only up grade i would do is a 50/50 map makes throttle more urgent and gets any lag gone, its the best to live with and makes the car faster by being more smooth, smooth power equals faster progress early power always good
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Maybe just a performance panel filter then. Even if for no other reason than it can be cleaned and reused. Lol.

I just called and spoke with John. Was on for over half an hour chewing the cud and discussing options. Seems a really sound fella and defo knows his stuff. Ive sent him my details as he said they send the van on tour so if he gets a few jobs in the area he can do it in person. That way he can check everything out in person and ensure all is well before doing anything. He can also personalise the map to work best with my individual car.
Maybe just a performance panel filter then. Even if for no other reason than it can be cleaned and reused. Lol.

I just called and spoke with John. Was on for over half an hour chewing the cud and discussing options. Seems a really sound fella and defo knows his stuff. Ive sent him my details as he said they send the van on tour so if he gets a few jobs in the area he can do it in person. That way he can check everything out in person and ensure all is well before doing anything. He can also personalise the map to work best with my individual car.
yes he's nice guy i've got a lot of time for him, a lot of mappers as they call them selves just instal a flash bought under license from a rolling road company, john dont his maps are mainly his own and his party trick is mapping something to suit the car ie live mapping and most charge a arm and a leg for that, he's fair always has been, he had a look at something for me the other day hmm well my diagnostics had a brain fart and turned out it would not read thermostat sensor circuit ie -48 all the time so i dumped it on him thinking it was a montronic at fault within the ecu. he could of told me it was worse than what it was and he done the honest thing ie plugged it in with snap on and it works lol. honesty and respect is a rare thing in the motor trade from my experience so when someone is blatantly straight its dam nice and i will back him all the way,, helps to bring back some trust in the human race to be honest.
by the way i dont get or expect anything from him for putting him forward to anyone i totally do it because him and his workforce are sound people and deserve it unlike some some
I couldnt agree more Mike. I found the same from the guy who did my timing chain. He was straight up about everything amd didnt try and get anything extra from it even though the warranty company were paying for it.

After he had given them the initial quote for the work he started the job and then found that there was a very slight amount of wear on a single tooth of the cam sprocket. He ordered a new one which I said I would pay for myself rather than try and amend the quote.

When I collected the car he wouldnt take any money off me and just said that the labour would cover it so not to worry. I dropped him a nice big box of beer off for being such a sound bloke. We were both happy with the deal.

Thing is even when he showed me the parts he replaced I could barely see the worn tooth but he was right. He must have eyes like a hawk. Seems like a perfectionist which is a good thing with a job like that
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