Actually it explains on one of the pics of the silkies on Feathersite http://www.feathersite.com/Poultry/CGP/Silkies/BRKSilkies.html that in Europe there actually are two sizes of silkies but in America there is only one recognized sized and it falls pretty much in the middle of the two European sizes.
There is a guy not far from me though that I bought some call ducks from that had some huge silkies, pretty ones too, that he kept for broodies.
I have a big white silkie called Kate Moss, she is the same size as my araucan and RIR. She is the nicest natured chicken we ever had, but the buff hooligans pick on her as she is quite timid.