This..
While Phenibut is a lot safer than benzos/alcohol, too much will cause BIG problems. Picture blurred vision, REAL slow reaction times etc. Not pleasant. The key is not taking too much. To that end, monitor your pupils. Too much phenibut is easy to feel, but before you get there your pupils will be overly dialated. The opposite is true for Kratom.
Ephedrine HCL will dialate pupils, but that kind of poly-pharmacy is dicey while driving. I've used phenibut for over a decade, ephedrine/ephedra/sida-cordifolia for over around 25yrs and Kratom for the past 3.
Three of the most effective, result producing nutraceuticals you'll ever find. But they need to be treated with much respect. Hope that helps...