Ok guys ill try explain how the lightened flywheel works in laymans terms...
Lets say u are going to push a box on the ground. If u have a light box, it is easier to push and quicker. If the box is heavy, it takes more time.
This can be related with the engine and flywheel. If the flywheel is light, the engine can get to higher RPM quicker, and if the flywheel is stock/ heavy, it takes the engine longer to get to higher RPM.
What this all means is that you can accelerate quicker due the the engine being able to rev quicker. This is the principle reason that people change flyhweels to lightened items. The only downside is that because the engine can increase in revs quicker, it also decreases in revs quicker.
Hope that makes sense to those confused.