The K&N 69-8009TWR Typhoon air intake system is a free-flowing, mandrel-bent aluminum tube air induction system designed to fit some Subaru WRX STI Turbo models. The restrictive factory air filter and air intake housing are replaced by the K&N Typhoon air intake which is designed to dramatically reduce air flow restriction as it smoothes and straightens air flow. This allows your engine to inhale a larger amount of air than the factory air intake. More air means more usable power and acceleration throughout the engine's RPM range. In addition to more power, this air intake system improves engine sound with more aggressive and deeper acoustics during acceleration. The 69-8009TWR air intake comes with a black rubber topped K&N high-flow air filter and a heat shield that installs into the original air box space. Air is directed through the intake tube into the engine's turbo inlet for a guaranteed power gain. The intake tube has an attractive red textured powder-coated finish that's made to last and it accommodates the factory mass air sensor. The oversized cone shaped air filter can be used for up to 100,000 miles before servicing is needed depending on driving conditions. This air intake is relatively easy to install usually in 90 minutes or less using existing factory mounting points. The tools needed are a couple of screwdrivers, pliers, a ratchet set and an Allen wrench. Some Typhoon air intakes are not legal for sale or use in California and other states adopting California emission standards while others are CARB exempt and 50 state legal. Check the K&N catalog or website for vehicle applications and specific CARB status for each vehicle and air intake.