If you can imagine 2 lines running parallel with the rear end from side to side. The 1 line being in the middle of the rear end. And the 2 line running through the bolts that bolt the 2 upper bars to the rear end. You want the bars where they bolt up to the rear to be level with the rear end and not at a angle. To fix that you will need to make new upper bar mounts on the rear end. You should have the out most upper bar mounts being the tallest mount and the inner most upper bar mounts(the ones closet to the center of the rear end) shorter then the outer mounts. Make sense? Kind of hard to explain.
Here is a pic of my top bars. Hard to see but the upper bars are mounted level with the rear end and not at a angle.