I was wondering if the Trim 2 was for tuning the fuelling in closed loop mode. It would be nice to be able to to tweak the mixture to make it pass MOT with a poor catalyst.
My MGF passed the test with 0.2% CO so I think the cat is OK.
After doing some testing with the Trim 2 buttons with my Gunson analyzer connected I found that they work in open loop only i.e just the same as the Open loop rich/lean buttons.