Get a matchstick. Break it in half. All you do is larkshead them into the bungee cord at the back of the sail. Increases bungee tension and deepens the sail. So, there you have it.
Blue dots are the old tow points, pinky-type dots are the Activated ones.
Can't see the bungee mod from here, but you can see the effect - the sail is flatter and more defined. Have fun with these mods - none of the measurements are writ in stone, but they do work for me.