For maximum airflow from a drop-in filter for your 08-15 WRX look no further than the aFe high flowing Pro5R. This oiled OE replacement drop-in performance filter allows significantly more airflow thanks to it's five layers of progressively finer mesh cotton gauze media. Washable and reusable for many cleaning cycles, the round topped pleats offer maximum surface area and deep pleats for excellent dust holding capacity for longer service cycle between cleanings. aFe's Pro5R ensures tight, no leak seal over the life of the filter.