SPL FRS/BRZ Solid Subframe BushingsFRS BRZ solid aluminum subframe bushings replace the stock mushy rubber bushings on your Scion FR S and Subaru BRZ to eliminate free play of the subframe relative to the chassis. This prevents the subframe from "bouncing around" under drivetrain torque or suspension load, maintaining optimum suspension geometry and reducing wheel hop. SPL's slide in shim system allows you to quickly raise or lower the subframe to fine tune the roll center anti squat