If you're going with the Wings West high rise, you might want to get longer bolts; the width doesn't really matter cuz you can just drill the holes in the wing larger if you need to, but the best way to tell is to get the spoiler, then see what bolts will fit. Also, you will need to drill two more holes closer to the rear window to hold the spoiler, so open the trunk and look at that lip that comes out around the edge of the trunk lid. The width of the screw should be about maybe half of that.
Mike