advice please.
I have a 1.8 rover K series super sport which is having trouble getting through the emissions test at MOT. It eventually get through but is hard work for the tester, i can keep doing this no problem but i'm trying to establish if there is a bigger problem waiting to happen. The only changes to the engine are DVA verniers and 52mm throttle bodies and a 4-2-1 power speed exhaust with cat.
I thought it might be the exhaust so a new CAT was fitted this year and its made no differences
Can anyone suggest the next logical thing to look at.
Thanks