The AEM 21-732C Performance Cold Air Intake System produces horsepower and torque gains by replacing your vehicle?s restrictive factory air filter and air intake housing. This air intake system was designed, tuned and dyno-tested to fit specific Subaru WRX models. Air enters the system through an oversized AEM Dryflow synthetic washable air filter for outstanding air flow, filtration and performance. The air filter is located in the original air box space and is protected by a heat shield which is designed to reduce intake air temperature and increase horsepower. The intake tubing is constructed from mandrel-bent aluminum featuring a durable gunmetal gray powder coated finish. This air intake system was developed to accommodate the engine?s factory emissions control devices including the mass air flow sensor. View the 21-732C vehicle applications to determine the legal status for each vehicle.