TOMEI OVER SIZE VALVE SET For SUBARU EJ 163403Brand TOMEI Product Number 163403 Compatible Car SUBARU Compatible Engine EJ Product Description Tuned engines require as much fuel mixture to enter the combustion chamber as possible. So a larger diameter design was selected to optimize flow rates. Due to the extremely high temperature conditions experienced in the combustion chamber during high power runs the durability of the valves were also addressed to improve resistance to high heat conditions.