There's a small "blink and you'll miss it" behind the scenes clip on the IM3 additional material(I know it's on the bluray, but i'm not sure if on D+), where Tony meets Maya Hansen at the door of his Malibu mansion before the helicopter attack. He's meant to be in the suit(And is in the suit in that scene in the movie), but was filmed wearing his normal clothes as it's the part where the suit opens up and he steps out. Anyway, he is walking on a huge wooden step, like a railway sleeper, and he walks along that, and steps down off it, as though the suit adds maybe six to nine inches to his height somehow. In the movie scene, there's a slight edit as he steps out. But in the behind the scenes part, you see him stepping down out of the suit, implying the suit adds to his normal height.