RS Mk3. ST250 and RS Mk2  K&N  Air Filter is designed to increase horsepower and protect your engine by reducing restriction and providing excellent filtration. The custom air filter is manufactured to replace the air filter in the 57S-4000 performance air box and it comes with a K&N embossed lid cap. The filter media can be washed and reused repeatedly.
This product has the removable bung for extra CBV noise!!
K&N9289