K&N Replacement Air Filters are designed to fit right into the standard OEM motorcycle airbox. No modifications are required by the owner, no jet changes or adjustment of the carburetors is anticipated or suggested. Customer modification of the standard airbox - removing the cover, drilling holes into the side or top will have a drastic effect on smooth carburetion. Modifications will cause the stock system to run lean and reduce horsepower. Keep your motorcycle stock and the new K&N Replacement Element will be good for the life of the engine.