The APR Valve Spring System is a high performance, lightweight upgrade designed to increase valve control and eradicate valve float common on many applications. APR's design specifications called for a valve spring, retainer and spring seat combination that doesn't overpower and snap the OEM valves or erode the aluminum spring seat, while still maintaining exceptional valve control. The result is an advanced design that's 28% lighter yet 20% stiffer than the high performance OEM EA113.K04 (MK6 R) setup and is proven to eliminate the OEM valve train's weakest link. We call it Performance Without Compromise! Fits various VW, Audi, Seat, Skoda, Cupura, Bentley, Lamborghini, and Porsche vehicles