[Raymonndo]

Hi guys,

Those of you with decatted downpipes have you been able to pass emissions? .

Thanks!

[Raymonndo]

335i that is

[tomwh85]

Don't you know a good mot friend?

[AlanYoro35i]

Didn't have a good MOT friend but i passed, did a loop on our local ring road first and ask them emmission first if u have a friendly mot place

[windymissile]

Get them warm/hot before you go in. Shouldn't be a problem.

Apparently mine were close this year but it's a 5 min drive to the test station..

WM

[Raymonndo]

Cool . Thanks all!

Anyone use additives or anything like that?

[AlanYoro35i]

only 99ron shell stuff, not sure if it make any difference..assuming you have secondary cats

[russjonesr]

I'm sure I have read somewhere that ethanol will also improve emissions?

[russjonesr]

Mine failed the MOT only on emissions, everything else spot-on! I have no C@ts at all....anyone know any sympathetic MOT testers in the Midlands?

Also considering this? http://www.n54tech.com/forums/showthread.php?t=31765

[Aragorn30d]

My brother had a pair of those magnaflow 200cell cats in his Audi S4, they worked pretty well, and no MOT/emissions issues.

Dont bother "swapping in and out", its pointless, the performance difference is minimal so just leave them on.

[old grey steve]

Mine passed emission's with Catless pipes no major issues at all it will depend on several factors getting the car warm helps, plus other factors

[Aragorn30d]

its quite simply IMPOSSIBLE to pass a UK petrol emissions test without cats.

A healthy modern engine, with no cats in the exhaust, will produce a CO figure of around 0.45-0.55%. The pass limit is <0.3% and sometimes lower.

If your car really does have no cats, and you passed an MOT, then the only possible reason for that is the MOT tester has turned a blind eye and done you a favour. If you've only removed one set of cats, ie just downpipes, then you should be able to pass just fine, so long as the remaining cats are warm enough.

[old grey steve]

Originally Posted by Aragorn30d

its quite simply IMPOSSIBLE to pass a UK petrol emissions test without cats.

A healthy modern engine, with no cats in the exhaust, will produce a CO figure of around 0.45-0.55%. The pass limit is <0.3% and sometimes lower.

If your car really does have no cats, and you passed an MOT, then the only possible reason for that is the MOT tester has turned a blind eye and done you a favour. If you've only removed one set of cats, ie just downpipes, then you should be able to pass just fine, so long as the remaining cats are warm enough.

With Catless downpipes in situ only as said mine was OK and have 2 MOT Emmission prints as proof, mapping will assist of course with CAT delete set up to accommodate the lack of primary CAT's, but with no CAT's in place as you say I think the word "you'll struggle" pwould be a slight understatement, I've never seen a Catless 335i on our MOT unit so cannot say exactly how far short of the required standard a fully Catless car would fail but I suspect it wouldn't quite meet the standard(though I could be wrong of course)but seeing how my downpipes effected the result, I'm fully aware that it's getting close to the borderline. Removing all CAT's got me for this very reason was/is a no no .

As for friendly tester VOSA are really clamping down with tge rollout if tge all new MOT server/database due later this month I think of various criteria things will change especially re VOSA inspecting ststions to ensure standards are being met

[RajB]

As long as you keep either the primary or secondary cats in place you'll pass no problem. Remove both and it's a definite no go.

I'm going fully catless so my AR catted DP's are up for sale. With no secondary and the AR's I got a test done to check and it did pass.