You can have an 8 yard GK and an 8 yard wee kilt, or you can have a 4 yard of either. But a greatkilt is double width, and that material up top is what goes over your shoulder. It also has nothing to do with the pleats. I'm very particular when I pleat mine, and have figured out just which lines to pleat to, and they're deep (my GK is a 6 yarder, so I have a bit more to play with).

Sliante,
Nick