Vascularity is based on low bf, how intense you are training and yea also supplements like arginine. But personally I noticed no difference after taking it for years and coming off it. Your veins will naturally expand based on your activity level and how much blood is flowing into the muscle. If you want your muscles swelling w/ blood than do some research on Time Under Tension. Also don't rest 3-5 minutes in between sets.. For Biceps I rest 45secs, Chest 1-1:30, Back 1-1:30, Shoulders 1-1:30, Triceps 1min, Legs 1:30-2min. It's enough recoperation time plus you are keeping the blood pumping and moving