ok autozen i think we dont need to go any further .you have your idea and i have mine.But unfortunately when you are driving at 80km/h and it brakes ,gues what both side bend.And ok lets say it was at idle and only the right side bends,would you only take the right side of or both heads.Gues what we would take both of ,and even if the valves are not bend ,the guids might be worn and the all famous left head gasket leaking.We would do all at the same time so the customer has a piece of mind drivind his 380,420 ,560 for another 200k without having to worry about it.