The reason why im posting this is because i heard that you cant use forged pistons in the H22A block without resleaving the block. Well ive did some research as to why this is so. The H22A use a extra tough Nikasil (nickel ceramic) lining in all the cylinders for better reliabilty (BMW, Porshe, Mercedes and other manufacturers have used this process for decades). The problem when using aftermarket forged pistons in these blocks (including the European maunfacturers which have ran into the same problem) is the rings and not the pistons themselves (i think). Most uses a chrome plating on the rings (which causes excessive wear on the Nikasil which causes the cylinder to lose compression and other nasty things). They are aftermarket forged piston manufacturers that use Nikasil friendly rings. Wiseco is one, but they do not stock pistons for the H22A (have to be fully custom). Either that or use JE's and get the Nikasil friendly rings from them or another manufacturer or use the OEM rings (i dont know if that is possible). Hope this helps anyone planning to boost an H22A. Anyone with more input to offer please do so as i am not completly sure about the piston thing because im not sure if the forged piston itself will actually wear out the Nikasil coating. Turbo Porche's have solved the same problem so I think that some of the things could apply to the H22A as well. Although i hear about the piston coming in contact with cylinder wall, im not sure if this would be an issue with the forged piston in the Nikasil coated H22A. Im doing some more research and will do post it here as soon as I learn anything new.