I know you are not asking me, but I monitor my BP and also notice great mental/mood benefits so I figured I'd respond.
I take 1g in the morning with a glass of oj. Within 20-30 min, it lowers my high normal BP (average 134/78) about 4-5mm Hg and this will last throughout the day until about late afternoon. I do feel that the PN in combination with the agmatine brings it a bit lower, but I have not yet checked as I have only taken the PN twice. I have tried it in the late afternoon when my numbers are higher and found that it will lower it more. It almost always seems to keep me in the 125ish/72ish range after taking it.
For my money, an OTC that also reaps great mental benefits and lowers BP that much is an absolute winner.