Strut mount flips allows the struts to retain the ability to 'drop' (or allow your strut to extend) to reduce topping out the stock strut. You are essentially moving the strut's movement parameters downward about an inch to keep it more in synch with increases to the spring height (spacers or longer springs). Regardless of how thick of coil spacers or how tall of springs you install, the stock struts have a fixed travel length. The strut flip is a technique to balance out the use of both the up and downward movement range of the strut. The CVs have a narrow range of operational movement as well... hence the need for the extended diff drop brackets on lifts (generally over 2 inches) which simply move the diff downward in order to keep the CVs closer to the center (for the most part) of its operational range.
