From the MoCO site
This Stage IV Kit was developed to deliver maximum horsepower from the Milwaukee-Eight® engine - all the way to the redline. The system-matched combination of larger displacement cylinders, free flowing CNC-Ported cylinder heads and a cam with the highest available valve lift are the starting point to building the perfect engine for the performance junkie. The addition of the large 64mm bore throttle body and high-flow injectors provides great acceleration from first gear through sixth and exceptional response at the twist of the throttle. Designed for a high level of flexibility, this package is ideal for riders who want stump pulling torque throughout the rpm range and also crave plenty of arm-pulling acceleration when you whack the throttle. Kit includes CNC Ported Cylinder Heads with Performance Valve Springs, 64mm Throttle Body, High Flow Injectors (5.5g/s), 4.075" Bolt-On Cylinders, Forged 11:1 High Compression Aluminum Coated Pistons and Rings, SE8-515 Cam, Cam Bearing Upgrade, High Performance Tappets, Multi-layer Coated Head Gaskets, Top End, Cylinder Base and Cam Cover Gaskets, High Capacity Clutch Springs and Plates.
Black granite highlighted
Increases power by up to 40% when compared to the Original Equipment engine configurations
Provides thrilling acceleration when twisting the throttle
Delivers increased response throughout the entire RPM range
Maintains flat torque curve from cruising RPM to redline
Can be installed without removing the engine from the chassis
Retains Original Equipment Factory Warranty
50-State U.S. EPA compliant
here some pics