I've done some more rooting about and found the following, which clarifies it all a bit:
Vehicles: Exhausts
Lord Teverson asked Her Majesty's Government:
Whether the modification or replacement of motor vehicle exhaust systems in order to produce a greater level of noise is in conformity with European Union type approval regulations; and what enforcement action they will take to discourage any contraventions of the regulations. [HL5603]
21 Oct 2008 : Column WA101
The Minister of State, Department for Transport (Lord Adonis): European-Union-type approval legislation in relation to vehicle noise is primarily concerned with ensuring that new vehicles meet specified noise limits and exhaust standards before they are permitted to enter into service. Mandatory EU-type approval requirements have been transposed into UK regulations.
Control of vehicle noise in service is governed by domestic legislation. Under regulation 54 of the Road Vehicles (Construction and Use) Regulations 1986, as amended, alteration of the exhaust system of a vehicle so as to increase the noise made by the escape of exhaust gases is an offence. The regulation forbids both the alteration of the silencer itself so as to make the vehicle noisier and the alteration of the exhaust system (by, for instance, replacing the silencer with one of a different pattern) so as to make the vehicle noisier.
At MoT, test vehicle testers are required to fail vehicles which are excessively noisy for their type. Enforcement on public roads is carried out by the police, who are able to take action if they suspect a vehicle contravenes construction and use noise, or other, requirements. They have further powers to address noise nuisance under the Police Reform Act 2002 and the Crime and Disorder Act 1998 under which anti-social behaviour orders can be served on the vehicle owner, imposing a ban from certain roads or even vehicle confiscation.
So, as I see it, modifying the exhaust to produce more noise contravenes the Construction & Use regs. Bugger. I'm currently running a de-cat downpipe and no centre box......and a Stage II tune, so it's good and "fruity" under power
I guess it comes down to Mr Plod and whether he's out to get you or not. Means
roadside testing is of no consequence, as they'd have to ask you to take the vehicle to a test station, by which time the original system has miraculously appeared back on the vehicle..........
And it would also throw up problems of any vehicle with an engine transplant, as there would then never be a 'standard' system they could refer back to. Bring on the V8 Series II I've got planned
