Ben Stearn

Hi, I have a 05 WRX which is fully de-catted. I was wondering what cat I would need to replace to pass the mot. Any advice is much appreciated, especially if you are talking from experience. Thanks

TimH

iTrader: (11)

My '05 STi *just* passes an MOT with a Milltek sports cat in the centre pipe. It needs to be be very hot.

Others are fine with a sports cat downpipe.

I also know of some people who keep their original OEM catted exhaust and swap it back in come MOT time. I know others who have found a "friendly" MOT station and don't need to go through this hassle.

FWIW, I got fed up of changing exhausts every year, so now keep my Milltek centre cat in place...I lost about 10 bhp so now "only" have about 515

beardo47

Friendly MOT testers are worth their weight in gold

Lunchmoney

For the last few years I always had to swap my exhaust over (or, more accurately, get my garage to swap them over) for MOT prep then swap back again after. But this year they changed MOT tester and it sailed through without having to do a swap. They didnt ask how the tester did, and we dont care.
My car is running a full decat, I prefer the experience completely (perfornamce, noise, feeling), so for me it was worth it.

Turbotits

iTrader: (2)

Its not just about emmisions. all cats fitted from factory should be in place. How the tester knows what was originally fitted is beyond me as theres no data.

gazzawrx

iTrader: (11)

As already said if 2 cats are fitted as standard then both should be fitted come mot time, however most testers wont know how many cats are fitted as standard to cars so generally just look for one to be fitted, youll need the main one fitted as i doubt the smaller one will be enough to clean the emmissions enough to pass the test. Just make sure the cat is hot before the test is done and you should be ok. If the cars left standing for a while before the test then tell the tester to run the emmissions after hes done the ramp work, that way the cat should of warmed up enough.