I'm not completely sure, but I do know there were Wildcats without the folding wing. What I am not sure about is if the FM-2 was that way. I don't beleive there were any Hellcats without the wing fold, and that adds weight as well. If you compare Mustangs that race with stock warbirds, they are considerably different, and quite a bit lighter. I remember "Huntress III" also had the wings clipped to be a bit shorter.