thanks for all your suggestion guys, and i appreciated much. it seems like high fuel consumption if equipped with turbo or supercharger. is there any other suggestion just to have a slight modification to boost up the power without severely damaged the engine 1NZ-FE for the long run? i might search something practical with optimum engine output as well as best engineering practice for engine modification. most probably one of you has an expertise to look it in macro and micro point of view.