Stage V

Objective: Generate additional power! This is an "anything goes" option, with the right knowledge, tools and money the sky's the limit.
Modifications: Stage IV + Boring out cylinders, lifters, springs, rods, stroker kit, you name it! 
Pros: Once you commit to this type of investment in time and money, you would be well advised to do some in-depth research into where and how you want to add mods and spend $.
Requires: Engine work (? hrs) to install modifications + 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 serious and professional engine work. You will never want to ride a stock bike again! A stage V development basically means, Accelerate until you see God, then brake!

After a Stage V modification your bike may need a number of additional modifications, not specified in any one stage since it will depend on the specific parts, 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.