So like the picture at the top of the page of the cyber gray, you see it only has the black "rail" slots I guess you would call them. Anyone know what is needed for an actual roof rack or cross rails or whatever you call them and how much? I find it odd that the LTZ does not come with it, I guess I never paid attention and assumed all you needed was the cross bars, but it looks like there are more "pieces" involved in this correct?