XDP X220 Series Head Stud Kit 2017-2023 GM 6.6L Duramax L5PUpgrade the OEM head bolts on your 2017 2023 GM 6. 6L Duramax L5P when you purchase the XDP X220 Series Head Stud Kit XD3017HS. Upgrading the factory head bolts is a must when start adding horsepower and torque to your Silverado Sierra. The factory bolts typically can't handle the additional pressure in high performance applications which can lead to the cylinder heads lifting. Upgrading to the XDP head studs helps to keep the cylinder heads locked