The increase in airflow provided by the filter results in a 3hp gain on factory displacement M8 engines, up to 5hp gain for 124'' big bore M8 enginesFits oval Screaming Eagle® Ventilator® air cleaners and M8 special models equipped with oval air cleanersPerformance air filter upgrade for factory HD Ventilator oval air cleanersIncludes spacers and everything needed for simple installation22% more air filter surface area than factory