When it comes to aftermarket performance products, Cosworth is no stranger to aftermarket car parts, or in motorsports altogether. They have been some of the founding fathers in racing, and this company was kind enough to manufacture a drop in factory style air filter for your 2008+ Subaru WRX/STI.
Cosworth Performance Air Filters are constructed from a proprietary synthetic, non woven single layer, pleated polyester filter media that requires absolutely no oiling. These filters feature OEM like fitment, and the filter housing is inject-molded from High Impact Polystyrene which means it will breathe well. Over 98% efficiency, and 10% reduced restriction compared to OEM filters.