Pulley's worth changing?

Just wondering if changing some pulley's on the engine do anything to it. Any gain or positive gain?

Bigger power steering pulley lets you do donuts and autocross without risk of blowing the pump by keeping pump rpms down.

On race motors with blowers it would, but not on a stock one. An overdrive pulley makes the blower spin faster and make more HP. Some use Aluminum pulleys, or eliminate all power stuff with a custom stand alone drive system. You could try an under drive pulley to free up some power by spinning the alt, wp, and ps pump slower, but that has it's issues too.