Vaguely interesting reading
http://www.dorset.police.uk/pdf/P03-200 ... ctV1_1.pdf
Section 4.4.8 list 'no silencer' or 'failure to maintain silencer' as non-endorsable offences
An exhaust with 'not for road use' would classify as 'no silencer' and is therefore NON-ENDORSABLE
Section 4.1.3 A VDRS should be issued unless 'the circumstances are so serious, potentially dangerous or in such flagrant disregard or previous WARNINGS as to merit issuing a fixed penalty notice'
There's also a couple of useful 'download and print out for future reference' links on this site
http://www.bmf.co.uk/pages/bmf_main_pag ... age_id=156
I can find nothing relating to repeat offences in this instance -the only ones I've come across relate to number plates where the DVLA have the power to cancel the regstration and issue you with a Q plate
Squiffy, If you are missing the noise I can strongly recomend getting a set of Remus road legals as mine are lovely sounding (every year the MoT bloke says 'I cant pass it with race cans on' and every year I take him outside and point out the E mark on the cans

)