RSS Semi Solid Engine Mounts - For Porsche 996 and 997 (Set of 2) Designed for the Porsche driver who demands the absolute maximum in precision handling, feedback and control from their chassis. With factory hydraulic engine mounts, the drivetrain will move independent of the chassis during acceleration, deceleration and cornering loads. This movement can upset the balance of the vehicle and create negative handling effects. RSS performance engine mounts minimize these effects by utilizing specialized polyurethane bushings which offer a firmer, more direct driving feel with optimum feedback.