I'm thinking of getting a roof box for a peugeot 807. It has 2 roof bars fitted at the back when not in use & that can be separated & moved up the roof of the car to required position. sorry, I'm not too technical! I've been told conflicting things about the roof bars. Are they good enough to carry a roof box/attatch the roof box to, or would I need to buy additional roof bars? Anyone know for sure?? And if they can't, what the hell are they for??