i just got an email back from www.fourstroketech.com about the z400. i found out that the have high comp pistons, cams, port and flow, valve springs, and even 440, 470 and 500 stroker kits!!. this is a gold mine for z400 owners. the way to get these itms are to email 4 stoke tech and tell them that you want to buy z400 parts. the have them but they are not listed on the site yet.