K&N Replacement Air Filter – Royal Enfield Bullet 500 EFI 09–K&N's high flow air filters are available as a replacement for your stock motorcycle air filter element. They are custom engineered to fit your specific application and are designed to provide low restriction and increased performance, while providing excellent engine protection for your motorcycle. When used as a replacement for the OEM air filter, modifications to the jetting may be required. Features: Designed to provide increased horsepower and