The process of compressing incoming air to create boost and power also has a nasty byproduct of heat. Heated air lacks the density to make higher horsepower, increases detonation and forces the ECU to pull timing. All of which reduce the power you are looking to create.

Easy solutions do exist for this problem and PERRIN? offers several choices for your vehicle and personal taste. For mild modifications and a stealthy look turn to our Top Mount Intercooler upgrades, available for Impreza, Forester, and Legacy models. These bar and plate cores offer more surface area per square inch than cheap tube and fin choices from our less worthy competitors and the overall size is more than 200% of the OEM unit! But Top Mount Intercoolers do suffer from underhood heat buildup and while excellent for mild performance gains the Front Mounts are the ideal choice for all out, bar none HP gains! Vehicle: Forester XT 2004-2007