Im not wild about manley valves ...was very lucky when one broke in my hemi just as I was shutting it off to pull the motor ,,,literally caused no damage ...pulled apart and replaced all the valves ,the old Manley severe duty valves were laying on my bench and i was working on my car then i heard something hit the floor it sounded like a glass breaking ,went to investigate and it was another Manley severe duty valve had rolled off the bench and had shattered ......I still have both of them put away for the doubters ...these valves have a step in them down by the head and both of them broke there ...I was just real lucky ...