[swamp2]

The notion that reducing mass, either fixed or rotating mass adds any power is 100% positively false.

Now it can appear on certain dynos to show more power, but it does not add power. Think about it - the engine produces the power, lossy components like gears and bearing waste power turning it into heat. Thats it. Rotating components only store energy. This was discussed extensively recently in a post about CF drive shafts. Please read that one. In short just remember Newton's law:

F = m x a , force equals mass time acceleration

Reducing mass, normal sprung mass or even rotating mass is simply lowering the m term. If F (basically the force from the engine at the rear wheels) is constant than a the acceleration goes up. It is slightly more complex for a system with translating and rotating mass like a car but that is the correct concept. You can increase the force or lower the weight to get faster but they are entirely different things physically.