Hi - Tim from Chris Knott's here.
Sorry for the delay - i've been away on business for a week.
I would recommend that you always declare every mod. We accept mods but if an insurer found out a car was modded through an accident, they may not pay you a penny. Also, they may pay out the other party & then sue you for that money due to the fact that you have a duty of disclosure. Effectively, anything done after coming out of the factory, ie. not factory spec, is declarable.
Trained assessors/engineers can spot mods and this may create major problems for you.