If you don't have a proper intercooler shroud for your stock or aftermarket top mount intercooler, then you are letting all the incoming air enter tour scoop without a proper shroud then you are affecting the surface coverage area of the intercooler by allowing all the air to escape around the intercooler, rather than hitting the face of the core. The lack of air flowing through the core can cause the intercooler to heat soak quicker, which makes the intake charge warmer while reducing power. And we don't want to reduce any power. Now you can eliminate this possibility by getting a proper Intercooler Shroud. RallySport Direct carries a great selection of intercooler shrouds for most Subaru Turbo models. Our friends at Grimmspeed, as well as Process West make many great examples that fit OEM, as well as aftermarket intercooler cores. And while browsing intercooler cores, check out our great selection of intercoolers, and make sure you don't have any boost leaks by inspecting your intercooler hose kits.