K&N has developed a high flow custom air filter kit product number RK-3931 for 2008 -2009 Harley Davidson Dyna FXD motorcycles. The oversized custom air intake assembly was developed around an original K&N high flow air filter and will fit neatly behind your Harley’s air filter cover. The K&N air filter is washable, reusable, pre-oiled and ready to ride. See the complete list of motorcycles below.

The RK-3931 is designed to get more horsepower from your Harley-Davidson engine, in fact K&N dyno testing shows a 6.54 horsepower increase @ 5100 RPM on a 2008 Harley Davidson Dyna Street Bob.

The cast aluminum back plate includes built-in internal breathers. Also, a bolted-in dyno tuned velocity stack decreases the restriction of air into the throttle body. The result is more power you can feel with outstanding engine protection.

Spacers and hardware are included to mount your stock Harley Davidson air cleaner cover and a bump-seal is used at the base to provide a perfect seal. Installation can be performed in 90 minutes or less.