So would mine but for the fact that I have tried that. Admittedly it is an aftermarket one but the new cat seems to make almost no diference whatsoever.

After a long run the figures were acceptable (but not zero) at idle, but only for a few minuits. then it was back to the old figures

I have checked it with one of those IR thermomotors and it just doesnt seem to be getting particularly hot. If I had the luxery of time I would try wrapping it in some of that ersatz asbestos to insulate it and see whether that made any diference.

The local rover "Dealer" (as you might expect) sugests a "Genuine" cat might solve it, but before going down this route I am trying to consider whether I might have missed something stoopid. Hence the question...

The Laser is frequently usefull since the current scan tool manufacturers dont seem to comprehend that people actually own cars more than ten years old.....