more compression makes more power. More compression makes more heat. More heat means your engine will detonate or spark knock easier. I have seen guys build higher compression engines, then crank the timing back so far to run pump gas that it defeated the purpose of the higher compression in the first place. Both forced induction and higher compression create more pressure in the cylinder, making more power when tuned properly. Nitrous is sorta the same principle, it basically creates a greater pressure in the cylinder. Basically, the more dense that you can make the air and fuel volume in the cylinder, the bigger the explosion will be when it is ignited. The bigger the explosion means the piston is pushed down with more force=more power. I hope this might have helped and not confused more. Now with adding more cylinder pressure, the engine will be moving alot more air into the cylinder and pushing alot more exhaust gas out.......this is where free flowing exhaust and intake components come into play. I'm one of those people who knows how things work, but have a hard time putting into words