MCA defines concours as: "Car as it was delivered to the original owner without modifications." Which means that the car could potentially have dealer-installed items. Although, the rules are setup so that if there is no documentation to prove dealer items, there could be a deduction for excessive use. A couple items here or there are fine, but installing everything out of the accessory book will most likely get points taken off. Just need to be consider the likelihood of such a vehicle, which is extremely rare.
So, anyway, back to the thing about requiring Marti reports, it just depends on the organization and what their expectations are.