RD Series Cold Air Polished Intake System (RD6068P) by Injen. HP Gain: +10.6 hp. Torque Gain: +9.6 lbs. x ft.. Includes: X-1013 Filter. The RD Series is made for the enthusiast who wants improved mid-range power. This cold air system positions a high-flow air filter behind the bumper, where it can take in cooler, denser air. The cool air then flows to the engine through a fee-flowing aluminum alloy intake tube. Cooler air contains more oxygen for more complete combustion and more horsepower.