You can mod them for extra boost, even more boost than factory:

Modifying your Power Steering Pump - GM Truck Central

 

Damn!!! Where was that when i was looking for it??? ive done multiple searches about it even back when my truck was completely stock and the best ive found was the tsb which ive done to customers trucks and it has cured the low speed hard steering.... Havent taken the high pressure valve apart but im sure they shimmed it or something because they do make a difference...