Any car making more than 80db in a drive-by test will fail it's MOT.
About bloody time!:yahoo:
Of course, two downsides to this.
1/ Three years of noise before the twits are due an MOT, on a new car.
2/ They could just put a standard exhaust back on for the MOT.
With regard to point two, I'd personally hope the hassle would put them off.