What is the legal situation with cars that have very loud exhausts?

What is the legal situation with cars using what I call 'exhaust boosters' to make their vehicles sound like formula one cars? They seem to be driven by young male drivers who are what are loosely termed 'boy racers' and drive really badly or dangerously. Have the manufacturers bypassed some laws or are the vehicles the result of backstreet conversions?

Asked on 23 September 2018 by Neil Littman

Answered by Honest John
Some manufacturers fit buttons to give their cars loud exhausts (Jaguar, Ferrari, etc.) Usually the idiots you see have modified their exhausts. There is an EU drive-by noise test where a car has to accelerate hard from 30mph in 3rd gear and the noise is measured after 100 metres. Audi deliberately damps the throttle response in the R8 V8 in order to pass this test.
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