F80 M3 Downpipes / Emissions

BennyC

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Evening,

I'm viewing an F80 M3 Stage 2 tomorrow. I've searched the forum on this and the wider web but would appreciate some feedback here.

Should I expect this car to pass MOT emissions with a primary cat delete / downpipes? Presuming the tester isn't retentive and spots that they are missing?

From what I've seen the answer is yes and the secondary (or both) cat delete would lead to a fail.

Of course I'll check through previous MOT paperwork if available but could anyone here confirm their own experiences?

Thanks.
 

Railgun

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FWIW even a secondary cat delete might be problematic. YMMV.

In the rotary days, we often dumped in a little extra toluene which seem to help. But I can’t recommend one way or another doing something like that for this platform.
 

karyog

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I've had mine fail with just primary cats deleted. Now I'm full decat
 

kimbow

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Evening,

I'm viewing an F80 M3 Stage 2 tomorrow. I've searched the forum on this and the wider web but would appreciate some feedback here.

Should I expect this car to pass MOT emissions with a primary cat delete / downpipes? Presuming the tester isn't retentive and spots that they are missing?

From what I've seen the answer is yes and the secondary (or both) cat delete would lead to a fail.

Of course I'll check through previous MOT paperwork if available but could anyone here confirm their own experiences?

Thanks.
That will fail.
 

D8ni3l

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They will fail on emissions with either the primary or secondary, or both deleted, guaranteed. The only deviation that ive found you can do after playing with a few cars is downgraded the ppf to secondary cats. This is because both cars have the same emissions levels so removing the ppf makes no difference. taking out the secondary cat will fail and definitely the primary one.
 

Jacko 11

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I have known cars pass with primary cat removed and secondary in place.
 

Railgun

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That would be a “friendly” shop as there’s no legit way it can.
 

BennyC

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Thanks for the replies, I'll have a year to source a friendly tester but will look to pick up some used primary cat's in the interim.

Can anyone here confirm if the M3 and M4 share the same primary cat's? Same engine but I'm unsure whether the layout and fitment matches. Part numbers seem to match: 7848041 7848044

 

turbo87

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Mine passed with only catless downpipes. Get it nice and hot and emissions will pass.
 

adie

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Can anyone here confirm if the M3 and M4 share the same primary cat's? Same engine but I'm unsure whether the layout and fitment matches. Part numbers seem to match: 7848041 7848044

Yeah they're the same for both M3 & M4... click on the part number in Realoem and it lists which models it fits
 

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