Mk7 gti downpipe help

[GT15JCG]

Looking to go full catless dp and stage 2.

I was curious to know if i was to put a 200-300 cell cat back on for M.O.T emissions purposes would it pull a check engine light? No need to have a separate tune for catted and de-cat

I.e I'd put the cat on blast to the garage and remove it once if hopefully passed the M.O.T (obviously making sure the cat is warm before test lol)

Thanks in advance

 

[Reggie Enchilada]

If you get a Stage 2 tune, then you wouldn't have to worry about a CEL for the catalyst system displaying. As for passing the MOT test, that will depend entirely on if the test requires an exhaust sniffer and the quality of the CAT that you get. A 2-300 cell sport cat, there's a 50-50 chance. With an ECE cat, there's a much better chance that you'll pass.

 

[GT15JCG]

If you get a Stage 2 tune, then you wouldn't have to worry about a CEL for the catalyst system displaying.

So stage 2 tune regardless on what cat i put back on for the m.o.t or anyother reason wont show a CEL?

 

[GTI Jake]

99% of stage 2 tunes turn off the downstream o2 sensors "readiness" for cat efficiency and emissions testing. So you'd need to flash back to stock for testing. Either an o2 spacer or the OEM downpipe will need to be used to pass depending on how strict you local testing is.

Theres zero different tunes for catted vs catless aftermarket downpipes, since the only thing you'll gain from catless is an awful smell to piss off those around you. The modern high-performance cats of today flow within 1-2whp. Not to be a broken record but there's countless threads covering all of this in far greater detail.

 

[GT15JCG]

Seems a bit of a waste of time to go back to stock just for a test, might work a little different over here in the uk.

Couldn't imagine people going back to there tuners for a stock map if they don't have the ability to flash it back themselves our tests "M.O.T's" are yearly

 

[Reggie Enchilada]

Does the MOT test require an exhaust sniffer to be used or is it just a visual inspection to see if a cat is installed?

 

[GTI Jake]

Seems a bit of a waste of time to go back to stock just for a test, might work a little different over here in the uk.

Couldn't imagine people going back to there tuners for a stock map if they don't have the ability to flash it back themselves our tests "M.O.T's" are yearly

He asked, I explained.

I live in South Carolina where not only is there no inspection or emissions testing, but there's literally no rules enforced on anything...its the Wild West down here.

With that said I've successfully defeated CEL on dozens of cars with an o2 spacer, but for some people its voodoo black magic and impossible for them to master. If you or the OP fall into that category reinstalling the OEM downpipe might be time well spent. To set "readiness" you need to drive about 150 miles, so guess wrong on the o2 spacer set up and pop CEL then the 150 mile drive cycle process needs to be repeated for the car to show "readiness".


As for flashing back to stock that's probably something to consider BEFORE tuning if its inconvenient for you and required in your area. Regardless if the stage 2 tune has readiness turned OFF its impossible to pass an emissions test unless they allow of system to be INOP which is rare.