leoncp11,
Yeah, I used the bottom screw that holds the sideskirt on to position them on the car first, then once lined up and happy with the look of them, I marked the mudflap with the end of a phillips screwdriver, took it off again, drilled the holes and used a cordless drill and phillips screwdriver bit with self tapper screws to hold the flap to the arch liner of the car.
You may have to drill the edge of the metal on the wheel arch lip at the top of the flap to get it secured to the are, I did
. It was a nerve racking experience I can tell you but it came out well in the end
. They also work 10 times better than the standard flaps and theres hardly no dirt up the side of the car now at all. Im toying with the idea of fitting the same type to the rear of the car.