Its all about the 2012 visual cat check regardless of emission pass or fail I believe.
Thing is the emissions is the very first test they do at my mot place and they don't look under the car.
The last thing they do is raise the car up on a ramp to test the steering etc and a full inspection underneath.
Have passed with decat countless times but my number could be up this year lol.
Only option is to send my front section to racetech to have a bolt in sports cat added like below.
I'm running this 2.5" monster at the moment.
Of course I'm going to take my chances but a sports car may quieten things down and give better off boost torque.
Joz