due to a lot of confusion on the block here is a pic of the sleeves that are used in this block. there is not need what so ever to go any other route in a closed deck h-series block. the blocks are as strong as they come from honda the only problem is the cylinders walls are not COMPATIBLE with forged pistons it has nothing to do with integrity. so you put a iron sleeve in the block to allow the compatibilty for the forged pistons.