Excellent service. I own a repair shop, and always use Clearwater Cylinder Head Inc, best service for a very low price. I have purchased 6 heads from them and always had a great experience. I don’t see why people are upset about the core charges being that they are rebuilt cylinder heads, there is always a core charge, just simply return the core and you are not charged for it, just like any other rebuilt part. I also have not had any compression or oil blockage issues with these heads on arrival, with major engine work people should be checking this before reassembling the engine to save time and money.