hey. i asked this same question before too. and someone told me to come to this forum to check out the FUEL MOD here on rs25.com.??never found it?? i posted in nasioc.com. if you look for my name you might find it. they said DOHC dont need it. i looked at kastle's fuel mod. and compared it to my intake manifold. looks sort of similiar. i still dont get why not do it on a DOHC.