Adjustable fuel pressure regulator, quick question.

[Swiggart]

I have read that i can change the setting a small amount and get my car to run more lean/ more rich with it. But i have also read that i can't because the mixture is read by the o2 sensors. I think i could do some quick, small changes with it and get my car running more stoich. I know the car doesn't use the o2's at WOT so would this help me in any way? I bought it and just curious what i could use it for, i think it could work in theory.