K&n Air Filter Rk-3931 Replacement Rk Series Kits

K&n's rk series was developed to get more horsepower from your twin cam harley-davidson engine. built around the legendary k&n high-flow air filter, the this rk series assembly includes an innovative powder coated billet aluminum backplate that eliminates external breathers and features a built-in, dyno-tuned velocity stack. the result is a significant airflow increase to the engine without sacrificing filtration. this rk series assembly retains a factory appearance by utilizing the stock air cleaner cover. guaranteed increase in horsepower and torque. replaces the stock air filter and cleaner backing plate assembly. fits behind the o.e. air cleaner cover maintaining the factory appearance. washable, oversized k&n high-flow air filter equals longer life. oversized black, powder coated aluminum backing plate provides solid mounting. dyno tuned velocity stack directs airflow to engine. built-in breathers replace external o.e. breathers (where applicable). washable and reusable. excellent air filtration. includes k&n million mile limited warranty.