im pretty certain there is no law against removing a cat, providing the car still passes an emissions test.
OBVIOUSLY the car wont pass an emissions test, but without testing it at the roadside, they cannot prove this!!
ive had my car checked over many times by police (they like pulling me over to check my car simply because its got a cage and such)
many times theyve looked underneith and must have seen my fairly obvious decat, but theyve never said anything about it.
However they then decided to give me a pg9 prohibition notice because my horn didnt work! i dont think they liked me