I have some experince with these heads as I had bought a set. When we got them I dropped them off at my machine shop to be looked over. I had had them port the heads before shipping them. My machine shop flow tested the heads and the porting job was all over that place. None of the flow numbers were uniform like they should have been. Different flow rates for each cylinder would have caused me issues from what my shop explained to me. Also the oring installed into the head weren't the same all the way around. There was different heights on the o ring all the way around it. Not sure I'm explaining it right. Some areas of the o-ring were higher and or lower than other parts. My machine shop also found a used valve in one of the heads and during the valve job that they did on the heads before shipping them one of the vlave stems had been nicked. My shop said the nick would have eventually caused the valve stem to break. They also explained that if the head gasket isn't designed for the o-rings it would leak. Needless to say the heads went back and I got my money back. The issues we found with my heads they were not aware of and said they would fix but I didn't want to chance it so I ended up buying a brand new set of heads direct from Ford and had my machine shop do all the work on them. I can recommend these heads based off of what was sent to me. If I had used them they would have cost me a bunch of money later to remove them. That is my personal experience. If you need heads I'd get a pair from Ford or from Midwest Auto & Diesel. Morgan Primm there is awesome and does good work but I'd stay away from these if you are doing anything above stock. Even on a stock truck I don't think I'd go the Big Dogg route. Just my experince from about 6 months ago. Maybe they have gotten everything figured out now but I can't confirm that.
