Mr Whippy said:
What if you buy a car with the kit already on?
You'd hate to buy a car with the additional accessories 'mud flaps' and find out that your insurance was void :rofl:
if you got it brand new, then no you don't need to declare it since the spec sheet should indicate that already.
if you got it 2nd hand, then you need to clarify first if the previous owner added it or came with the car already.
your insurance will not get void, but when you get into an accident the accessories you added will not be covered(at least that's how it works here in our country).