Power steering pump question?

My power steering pump is slowly loosing its power. At a dead stop it hard to turn the tires unless i put it in neutral and gas it to get the pump going better.
My question is, do they make a heavy duty pump aftermarket instead of replacing it with an OEM or scrap yard pump?? I was also told that if i put a smaller pulley on it, i will pull more power on it but i have no idea if that is true or not which is why im asking these questions. Even if i got a smaller pulley,(from where or how, i dont know), but wouldnt the belt become loose??
Hope these questions arent to stupid cause im new at all this and could use your guys help. My XJ is a 95 with 5" of lift and many add ons so its far from stock hence the question of wanting an aftermarket pump thats better then stock.????
THANKS.

Just replace the pump. Unless you're going to get silly with your steering system or add a hydraulic winch, you don't really need extra pressure.

Also, I'd not want to under/overdrive the power steering pump. Alternator, sure. Water pump, maybe. Fan, OK. But, not the power steering pump - you just might need it to work like it's supposed to...

5-90