This is the top-of-the-line dual spring set up for engines designed to rev up to 8500rpm. VW650 Dual Valve Springs drop-in to heads machined for VW diameter dual springs. 

VW650 Dual Valve Springs are designed for extreme endurance so we use a NASCAR grade proprietary material that has unsurpassed high cycle fatigue life. These springs have extensive surface finishing including nitriding, polishing, heat set, and a micro shot peen. For the strip or street, the VW650 Dual Valve Springs will hold up to the most demanding driver.

Installed height of 1.540" gives you @ 160 lbs. of seat pressure, and @ .630'' lift you have an open load of 420 lbs. With the VW650 Dual Valve Springs you can run up to .630 lift, if your heads are properly set up!