Hi Lads I got the lambda sensor replaced but she is still failing on the CO reading for the emissions on the NCT. I figure it must be the Cats at this stage would anyone have a downpipe with a decent cat. Bit of a pain as all im going to do if she passes is to put the full H+S system back on. Any suggestions would be great. I may look at a cat back system that would give me the same grunt as the full catless system but without the hassle of swapping out the systems every year for the test.