3" Velocity Stack Features Impressive horsepower and torque gains on engines running modified and ported cylinder heads or intakes with larger throttle bodies Great performance part for racing and for those that want to head to the track on the weekend 3" tall billet aluminum for M8 throttle body bolt pattern 4" diameter opening with an internal taper down to 2.4" ID matched to 62 mm throttle bodies Includes gasket and hardware Made in the USA Will require a custom breather system or will not bolt up to aftermarket air cleaner backing plates that have internal breather system Manufacturer Part Number: 5400 Why Shop Tucker Speed? Harley-Davidson specialists with real-world parts and performance experience Fast shipping Expert technical support from a motorcycle shop that knows the products we sell Performance parts and accessories we trust on our own motorcycles