Hotchkis Sport Suspension 19107 2008-2010 Challenger SRT8 Sport Coil Springs. When we decided to manufacture coil spring for the Challenger we took our time and researched other springs on the market. With those springs in mind we found a great combination of performance and comfortable ride characteristics. Our springs feature a linear rate design and come complete with urethane bump stops. Drop: SRT 8 Models - Front 5/8 in. Rear 1 in. Can Also Be Used On RT Models for Front 2-1/4 in. Rear 2-1/8 in. drop. For cars equipped with self leveling Nivomat suspension lowering springs cannot be used without changing the struts. Bilstein offers performance replacement struts for these cars that offer great ride characteristics and performance.