i have a z with lots of mods as seen below, and i still tear it up with my pred. with my dad riding it, i beat him by 3-5 lenghts depending on my launch. OH, he weighs 80 pounds less than me! my z really runs good too. i raced a guy with a 450 z and beat him by 2 lenghts, but i rode the guys quad before we raced and didnt think it was as bad as a 450 should be. i think he may have only done a bore kit and nothing else (cams, valves, port and polish).