The fact of the matter is that unless you reduce its noise or get an mot to state the noise is not excessive then you are gonna get busted, thats all im trying to get across, i fully agree with all the grey areas that are mentioned but you aint gonna get out of it unless you do as they ask. You could fight them all the way but it aint gonna get you anywhere, if you dont do it within the time limit then they can take your car and you wont be able to stop them unfortunately, bit excessive i know but what can you do?