Objective: Take advantage of additional power generated in engine by redistributing how that power is transmitted into the drivetrain by changing the cams.
Modifications: Stage I + Cams
Pros: No cylinder work; rider is able to select what part of the power curve he wants to derive most power (Top-end, mid-range or out-of-the-gate)
Requires: Engine work (5-6 hrs avg) to install new cams + Dyno-tune - which is expected to deliver higher torque & horsepower, more efficient combustion (which may lead to better fuel economy), cooler engine running temperatures, and better throttle response.
Cons: Requires some engine work. You will never want to ride a stock bike again!
After a Stage II modification your bike may need a number of additional modifications, not specified in any one stage since it will depend on the specific parts and previous modifications, your engine and the miles on it. These modifications could include lifters, push-rods, valve job, valves, valve springs, cam plates, oil pumps, clutch kit, etc. One modification that is highly recommended after a Stage II is a heavy-duty clutch spring since the power generated will put a lot more pressure on your clutch.