the problems with those sleeves is that they restrict coolant flow around the top of the cylinder, which decreases ur cooling ability and can sometimes cause strange problems with warping around the head, u want a sleeve that is equal thicknesses all around, something that bullet proofs ur bottom end but also allows a good amount of coolant flow around the cylinders, if that makes sense. upgraded radiator and fans help but ur still not gonna be getting a good amount of coolant to the top of the cylinder due to excess metal in the way. blah blah blah hope that helps clarify things