Get a surface plate from amazon and 600 grid sandpaper Remove the stud on the cylinder and sand on the surface plate the head and cylinder until the surface are totally flat and free of dent. When putting the gasket it supposed to have an E mark on the gasket marking the exhaust side. Also you can use gasket spray with the OEM gasket. Torque the nut to the correct specification and recheck torque after each first 3 hour of operation.