not always xtr, if you think about it your insurance is not valid, so they are under no obligation to pay out at all. additionally you could be prosicuted for driving without insurance. if the only cover that was broken was the fully comp 'bit' (ie not the third party 'bit') then there would be no reason for someone to insure (say) a 1 litre nova then stick a 2 litre turbo'd engine in it and not tell the insurance..