Stiffer valve springs designed to fit stock retainers that will extend the revving capabilities of your valvetrain to the 8,000 rpm mark (6,000 on TDI models). In addition, the SportTuned valve spring set will eliminate potential coil bind on high lift cams. When properly installed they will allow up to 0.500 inches of cam lift. These are a good idea for any high-performance engine. Spring shims included.