Injen Cold Air Intake 2003-2003.5 Mazdaspeed Protege TurboThe Injen RD series is a cold air intake system for the enthusiast craving mid range power. The intake tube is strategically placed behind the front bumper to acquire colder denser air. Although most of the Injen RD series are a one piece design several are two piece designs due to the mass air flow meters. Every Injen RD system is certified or pending by the California Air Resource Board and backed by Injen Technology's limited lifetime warranty.