I think you may have mis-understood. I have a (Miltek) sports-cat (and am insured with Greenlight). It's just a different spec of cat, but still a cat and it still passes MOTs.
Re: Agreed Value Policies now available for FCCUK#68528 26/11/200617:5826/11/200617:58
Quote: If the car is manufactured after 1993 the vehicle must have a catalytic converter in place or it will fail its MOT. So we cannot insure any vehicle made after 1993 that does not have a Catalyst as it is not road legal.
Just to be clear, the car must have a cat fitted, even if it could pass an emissions test without one. IIRC the law was framed so that a certain catalytic converter manufacturer created lots of jobs in Europe with their new factory.
Re: Agreed Value Policies now available for FCCUK#68529 01/12/200620:1601/12/200620:16