Sorry dude, it was definitely NOT a GTR, didnt have the PHAT rear guards or the rear splitter, the wing looked like a GTT one and I didnt see a GTR badge either - I am 99.9% certain it was not a GTR, I would assume it was a GTT but could have been the GT-V or even just GT, there were I think 200 of those made [GT-V].
Sorry about the digression.
I agree with Adzmax - tell the insurance company as much as you can and if you need to make a claim, you can be safe in knowing they won't find anything to reject the claim with
Just Cars [& some others] are ok with Mods as long as they are legal AND you tell them!