Don't think of boost making power. You'll get horribly confused and want to smash your head against the wall.

In a way, high boost is a bad thing.

You see, boost is a resistance to air flow. Blowers, turbos, and all that are cramming more air into the engine than it can handle. When that happens, the air stacks up in the intake and pressure goes up.
When pressure goes up, heat goes up. Heat is a bad thing.
A really efficient engine will take more air than a less efficient engine.
Example:
Engine A is a 360 with stock heads, fctory cam, and stock manifolds.
Engine B is a 360 with a killer set of heads, blower specific cam, and excellent exhaust.
Both engines have the same blower with the same pulley ratio.
Engine A will make 450 hp at 10 psi.
Engine B will make 500 hp at 6 psi.

Engine A can't handle the air flow. It barfs up all the air. The air stacks up in the intake as boost because the blower is shoving it in but the engine can't use it. Think of it as being constipated. Air temperature goes up. Efficiency goes down.

Engine B has the hardware to actually use the air you're feeding it. That means air moves through it easily and there's less air backing up and making pressure (boost).

Since engine B is doing such a good job you can change the pullies and start shoving more air into it. Change the pullies until it makes the same 10 psi as engine A and you'll have a lot more horsepower. The air will still get all clogged up in the intake and temperature will climb but the better engine is making more power.

There ya go. Clear as mud.