Can anyone suggest the best/right cartos for higher voltage? I use smokteck lr 1.7 and dual coil 1.25 with my 3.7 volt pv's. I just got a 3VO VV which has 3 settings... 4, 4.5, 5 volts. (3.8, 4.4, 4.9 volts underload) What single coil cartos would work best for the 4.5 and 5 volt settings?