Go big or go home. With the largest displacement of any Harley-Davidson® Stage Kit, this 114CI to 131CI Stage IV Kit is designed to deliver maximum horsepower – all the way to the redline. Packaged with patent-protected cylinder technology, it allows for the largest bolt-on engine upgrade to any Milwaukee-Eight motor. Features new CNC-ported heads with 1mm bigger valves and fully machined combustion chambers.