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Discussion Starter #1
First of all, Happy New Year.

The question is a simple one, really. I think.

Assuming that when I go to an MOT centre I go as a regular punter as opposed to going to a mate who might be able to turn a blind eye to certain things (which is increasingly hard these days anyway with VOSA doing everything on computer)... do I actually need to have all the cats in the system to pass emissions?

I know my E39 is OK because of its age, but what about the F10?

If I go for a funky catless downpipe in the quest for more power (because we need more than a stock M5 in the UK, right?) then will I be screwed in a coupe of years when the first MOT is due?

Ta.
 

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As far as I'm aware yes, you will be.

My E39 has VM manifolds with 100cell cats and will no longer pass an MOT with them fitted. The CO reading is just too high. It's not miles out but out never the less. Go catless and you've got no chance of getting through. Id be happy to be proved wrong though.
 

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Discussion Starter #3
Thanks Dan.

I thought my E39 was OK because it's before March '01 so falls into a different emissions regime. Guess I'll have to check again.

Good to have my suspicions confirmed about the F10 though.

Also good you've reminded me about getting my manifolds out of Johannes' lockup and actually fitting them... A 2017 project I think!
 

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On a slightly different note, did you see the blue F10 M5 at the meet last week, which had been de-catted? Did you see the HUGE amount of [email protected] that came out of the back when he 'blipped' the throttle? It was like an old bus. Whilst it sounds great, I wouldn't want that much smoke coming out of my car under high load.

If there's a way to get bigger downpipes, which keep it legal, then I'd be very interested.
 

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my e34 was de-catted when I bought it and it failed emmissions by an order of magnitude. I think my Celica GT4 (alltrac) is decatted also. The logic on a turbo car (or certainly an old one like the Celica) is that this dramatically reduces lag. I'm doing research on the Celica but there are those who say sports cats make a real difference. On a modern car like the F10 I'd be surprised if lag is a big issue, and would therefore probably keep stock.
 
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