The difference is Steeda pulleys are 2-piece and Saleen pulleys are 3-piece. The Steeda pulleys have no alternator pulley. The reason why is that the 05+ cars have a one-way clutch on the alternator to prevent the belt from jumping when you let off the throttle at high RPMs due to the inertia created by the rotating mass of the alternator. Take your belt off and spin the alternator both ways and you will see what I'm talking about. The Saleen pulley must incorporate this clutch which is why the cost is so much more. BBK and some other cheap 3-piece pulley systems do not have this and include an alternator pulley, stay away from them. In my opinion the alternator pulley is not worth the difference in price, get the Steedas.