The Big SF Intake increases the inner diameter of the intake tubing to a massive 3", increasing the cross section of the intake and allowing the MAF sensor to read lower for the same amount of ingested air. This intake is the choice for higher horsepower builds. Cobb also provides maps for use with their Accessport Tuner to extract the most power possible out of this mod. Cobb is currently utilizing this intake to dominate the Redline Time Attack AWD Modified class.