K&N 57-3503 Cold Air IntakeK&N 57 3503 Cold Air Intake The K&N 57 3503 FIPK air intake system replaces the restrictive factory air filter and air intake housing in some Honda Civic and CRX models. K&N intakes are designed to dramatically reduce intake restriction as they smooth and straighten air flow. This allows your engine to inhale a larger amount of air than the factory air filter assembly. More air means more usable power and acceleration throughout the engine's RPM