Silent rubbers made in the USA by Clauss Studios from polyurethane.
Significantly firmer than the original rubbers, the Clauss Studios rubbers reduce the vehicle's own movement to a minimum. This makes the vehicle feel much firmer and the dampers respond more quickly, but at the same time you also lose some comfort.
Simply replace the rubbers with the original ones and you're done.
NOTE: The rear rubbers for GT, GTS, GTV only fit in the standard suspension struts, not in the BGM shock absorbers.