actually no, stillen, JWT ecu upgrade alters it, but to tune, the apex is the way..
i know a guy at Z1, who has a program that you can change anything on the ecu. to change the a/f on a Z, most Z owners go with an apex-afc2, its a great device, maybe not for a honda, but for a Z its good as it gets.
the afc alters fuel, not MAS voltage output. as of now there is no stand alone for the Z, but i been told AEM is trying to make one but its gonna cost a arm and a leg.
hardcore?? stillen(overpriced) and JWT(great company) are hardcore, not really?? u wanna go hardcore on a Z, throw on some td05-20g on it..now thats hardcore..