Later style 5S blocks (especially 98+ blocks) have a more closed deck with the coolant passages in different locations. Using a 3S head gasket would block off approximately 90% of the coolant flow. In the past we have used modified stock 5S head gaskets, but that is no longer necessary with our 1.0mm 5SFE (closed deck style) multi-layer steel head gasket. This new head gasket provides the maximum coolant flow possible with the later 5S style blocks. This gasket has been tested on both Gen 2 and Gen 3 heads.