Dual-rate lowering coil springs improve the handling, ride quality and stance of your 1967-1970 Mustang. StreetGRIP coil springs are CNC cold-wound from high tensile premium steel by then powder-coated for long-lasting, consistent operation. The dual rate design gives you the best of both worlds. The "soft" spring section helps your Mustang to transition over small road irregularities with comfort. As the vehicle further compresses the spring, such as when encountering large bumps and high cornering loads, the springs transition to the firmer spring rate to support aggressive bump and body roll movement. Using our exclusive test track, RideTech works closely with Hyperco, its technology partner to develop Mustang-specific spring rates for exceptional performance and comfort.