The PERRIN Performance boost controller cover for the Subaru STI is constructed of 5052 plate aluminum with precision bends and mounting holes to fit perfect under your hood. Aluminum construction will resist corrosion in those states with salt used during the winter time. Besides being a sleek new cover this part also provides a clean custom mount for your aftermarket electronic boost control solenoid. If you are using OEM boost control, no worries this part provides a custom mount for that as well. Powder coated for protection from the elements, the textured finish will look awesome for years to come.