Aero's with sidepipes had definitely be careful.
The S2 with the single pipe has failed a drive by test at a track and I was told not to bother trying with the Coupe.
With standard exhausts the Plus 8 "just" passed the test at Castle Combe.But that was in standard mode and not moving. When driving in Sport Mode it is a lot noisier and has pops and bangs.
It is my understanding that a vehicle has to meet the dB value on the V5, or its homologated reading. Over the years permitted levels have reduced, so older cars can be louder.
And then there is the MOT. As has been said, measuring a bike noise level is well nigh impossible, I was once required by a nice Police Officer to get my Triumph Thruxton (with aftermarket exhausts) checked. The local MOT guy said "I'm somewhat deaf, but it sounds just right to me. He then told me that in becoming qualified as a MOT tester there is no specific hearing test and he never wore his hearing aids to work....
