Any insurance company trying to get out of paying because of a sticker would have to be VERY bold to fight that in Court - no sensible Magistrate or Juror would consider that to be anything other than unreasonable. And even if they did decide not to cover, it would only be their liabilities in relation to any Fully Comp payouts to the policy owner, not payment to 3rd Parties as the result of any accident. If that were the case, nobody would ever get paid anything for any collision, so easy would it be for insurers to claim that the box of tissues mounted on the parcel shelf constituted an undeclared modification.....
And in terms of 'Factory Specification', I can probably quite confidently state that no 2 Morgans have ever left the factory the same - and even if you asked them what the standard specification actually was, they'd not be able to confirm what was in place at the time manufacture.
Overall I completely agree that as owners we need to be upfront with the insurance company, but they cannot simply choose to swerve claims on thoroughly unreasonable and unrelated grounds.
/RANT=OFF