de catted cars will be very lucky to pass fast idle test. To be fair with MOT laws and further euro emissions coming in to play even tho they only effect newer cars. Its going to be increasingly more difficult to get a car through an MOT with out a cat..

The real probblem with the law would be if VOSA were out doing roadside stopo checks for roadworthyness and making sure cars ID's were in order as they often roll about on the floor checking stuff.