Cool video on how a turbo works.
 

Neat!

very good

there is only 1 real way to get more power out of an engine, burn more fuel and air (well oxygen to be specific). How thats done is up to the individual. You can increase the displacement, let the valves to stay open longer, use forced induction, use cold dense air, nitrous oxide, and so on. All of these things are different ways to add more oxygen. If there's more oxygen you can add more fuel. More fuel and oxygen burning means more power