XDP X220 Series Head Stud Kit XD3018HSReplace the weak OEM head bolts on your 2011 2021 6. 7L Powerstroke with the XDP X220 Series Head Stud Kit XD3018HS. Upgrading the factory head bolts is a must when you start adding horsepower and torque to your Super Duty. The stock head bolts can struggle to handle the additional pressure in high performance applications which leads to the cylinder head lifting. Upgrading to head studs helps to keep the cylinder heads locked down and avoid head