K&N Drop In Air Filter - Subaru WRX 2004-2005 / STi 2004 (+Multiple Fitments) Upper Control Arms This item is non-returnable

This item is non-returnable

piston style diverter valves have slower response times and inconsistant operaton

Reduced NVH

*Does NOT fit early model S5 vehicles with 4

K&N Drop In Air Filter - Subaru WRX 2004-2005 / STi 2004 (+Multiple Fitments) Upper Control Arms This item is non-returnableK&N washable, reusable High Flow Air Filters feature a state of the art design of layered, oiled cotton media engineered to improve airflow and capture contaminants, and are designed to provide an increase in horsepower. Each performance air filter is reusable, engineered to last for the entire lifespan of your vehicle, and backed by K&Ns 10 Year Million Mile Limited Warranty. K&N drop in replacement filters are designed to install easily into your