Adding pressure will not give you power, taking away pressure will take it away (maybe)
My stock pump will hang at about 60ish at idle and drop to the mid 40s pulling my 5er when standing on it (watching egts of course). My veggie pump will hold about 75 psi and will not drop even when grossing 23k and standing on it. do I feel a difference? if there is one, i don't really feel it. maybe there is a difference on the dyno, but my butt-dyno says its the same. If you are not going to do a veggie conversion, I say go for a RR. They are good and your truck will like it better. The down side is they are $500+