Each spring is loaded in the spring tester at the factory, then compressed and the CNC load cell measures the force for a variety of spring lengths. This allows BMR to offer a LIFETIME WARRANTY against spring sag.Blending aesthetics and performance, BMR has designed the SPD763 for the power adder crowd who want great all-around performance without worrying about the front-end sitting too low. These springs are designed for vehicles with the extra front-end weight of a supercharger or turbocharger kit. These lowering springs feature a fine-tuned spring rate (170 lb/inch front, 740lb/inch rear) to give you great performance and a smooth ride. The linear spring rates offers plenty of support, while remaining soft enough for great weight transfer. When performance and looks are a must, rely on BMR's suspension!BMR's suspensions SPD763 lowering springs are available in red powdercoat for long-lasting good looks. Front and rear springs are available separately (SP089 front, SP088 rear). Installation time is about 3-4 hours. Proudly made in the U.S.A.