Heavy duty STI hardened strut top mounts reduce compliance under high cornering and damping forces. The OEM rubber tops are made of soft rubber to help make the ride quieter and more compliant. But when upgraded struts or coilovers are installed the rubber tops make for a bouncy ride. Replacing them with these stiffer Subaru upgraded mounts reduce the bounce and provides excellent suspension feedback and better steering feel. The slight increase in NVH (Noise Vibration and Harshness) is well worth it for those looking to make their OEM suspension or aftermarket suspension more solid feeling. Direct bolt on replacement of stock parts.