Teemu measures his droop from the pit board to the top of the axle. I don't really like doing it that way. I measure the droop as above ride height. Set the cars ride height where you want it. Then lift the car by the center of the shock tower with the shaft of a hex wrench just until the tires come off the ground. Then use your ride height gauge and measure your ride height again. The difference is your droop. If you set the car to 5mm ride height and lift it up until the tires are just touching and measure again and you get 8mm, you have 3mm of droop. Then use the actual droop gauge to make sure both sides are even. I usually run between 3 and 5mm of droop above ride height.