Ive got the screwdriver mk2 with a 510 converter and LR carto tank but you may know that with a ICR 18350 battery on a full charge i am vaping at 4.2 volts for about the first 10 to 12 drags, then it drops to 3.7 for a long 10 to 12 hours. Ive gotten addicted to the first few drags at that higher voltage so ive got to go up in voltage what is a good vv mod for a really cheap price mad vapes VV boxmod has been one thing i keep looking back at but is that the best for my money? Any suggestions??