Subaru SF Airbox 2002-2007 WRX, 2004-2007 STI, 2004-2008 FXT712160 DESCRIPTION The SF Air Box adds the benefits of a cold air intake to the outstanding performance of the SF Intake. The factory inlet directs cold air from the front grill to the SF Airbox, which encloses the SF Intake. Hot engine bay air that robs horsepower is prevented from entering the intake system. This unique design also separates rainwater from the intake air, eliminating the water ingestion issues that plague in fender cold air intakes.