Didn't sign a sheet when we bought a new Kawasaki (restricted by dealer) and the sheet was an added bonus when p/x with the dealer because it was proof rather than hearsay.
Great you didn't sign it, sorry but it don't make it legal just because you didn't get asked. It may be that factroy kits are different to the after market kits, and there is a difference if it is a model manufactured from the factory to make less than 33 bhp (but you still cant fit extras to make it go faster) If its an under 33 bhp bike then old bill have to prove its making more than that, but if the bike was originally making over 33 then its YOUR job to PROVE that is currently meets the legal limit, police dont have to prove anything it assumed to be over 33 bhp unless proven other wise.
But lets get this straight if you were supposed to, its YOUR fault if is not done, its up to YOU to make sure you understand the restrictions, If you are on a restricted licence it is up to YOU to make sure the bike is restricted, it is up to YOU to prove it if asked by the old bill. If you get caught without you are looking at more than 6 points, for the two offences of driving other than in accordance with your licence and no insurance.
I have never heard of ANYONE who was on a restricted licence NOT being required to produce a restriction certificate if the bike was originally on the over 33 bhp list. I will take the word of any of you who tell me that you can get away with a Dyno certificate but personally I haven't come across this.
I really cant see what the discussion is all about, if you have a non 33 bhp bike you have to buy a restriction kit the cost is the same wherever you get it, at best you save the cost of fitting, and you would still have the cost of dyno testing if its applicable. For the sake of £100 save yourself the possible grief and just get the kit and get it fitted, it can be fitted by any mechanic it dont have to be a main dealer, afaik any mechanic can fit it and sign the paperwork.
Personally speaking, if I stopped someone I would want proof then and there that the bike was restricted or you would be walking home.