Subaru Impreza WRX STi 2004-2005 AEM Polished Cold Air Intake System

AEM cold air intake system relocates the filter outside of the engine compartment to deliver cool air inlet temperatures. Cooler air carries more oxygen, which translates into a more intense explosion in the combustion chamber to create more horsepower and torque. But that's only part of the power equation. Tuning the inlet pipe in length and diameter to match the engine's resonance helps move more air to the cylinders, and this tuning allows us to deliver large power gains.