Ok from what I've searched the h22/h23 and f20c use FRM (Fiber reinforced metal) technology....but I've also read that it uses .5mm nikasil as well. Is this nikasil is what the rings are actually contacting? Does that mean any block with Nikasil requires use of special pistons? The k20a uses nikasil but to the best of my knowledge it does not use FRM. Does that mean it requires special pistons such as Mahale for the h22? I am very confused and would like some clarification. Thanks.