One of the new tunable components on the new Shelby GT500 is the addition of a wicker bill or “Gurney Flap” on the rear. Introduced by racing legend Dan Gurney nearly 40 years ago, the Gurney Flap is essentially a tunable element on a low-drag spoiler. On the 2010 Shelby GT500 it sticks up about 6 mm and is positioned at a right angle to help create downforce. Tuning options include using Gurney Flaps of different heights or removing it altogether.