2001-2016 6.6L Duramax Valve and Spring Kit Performance (110090080)Description The intake exhaust valve, valve seal, spring, spring seat retainer keeper kit comes standard with each PPE Duramax Cast Iron Cylinder head. This kit is specially designed for the GM 6. 6L Duramax and contains the components for both driver and passenger side cylinder heads. The valves are fully nitridated and reinforced for superior durability and reliability. The tapered valve springs' higher spring rate and lighter valve train weight