The cylinder head stud sleeves, according to Shell Power article, were to allow for the head studs to have all of the clamping force necessarily without cracking the aluminum head. As far as I was aware, those sleeves are for when a stud (or bolt) passes through a water jacket or the intake/exhaust ports.
Anyone have a different experience? Seems using a sleeve that takes the clamping force off of the head is the opposite of what anyone would ever want.