Yes, their is a service bulletin out on the headbolts. Mecury wants them replaced. Some were caught at the factory and changed. Have a dealer run the serial numbers on your motor in Mercury Marines computer, they can tell you if the upgrade was already done or needs to be done. Not likeing the way Mercury says to replace them, but I guess they know best. They want them replaced one at a time. Take out the old replace with the new, and move to the next in the same pattern used to torque the head.