I've convinced my friend to move away from cigarettes and go to vaping. It's been a week now and he's thinking of going back to cigarettes. I started him on 70/30 Vg/PG and for some reason he's getting sore throats. Can even such a small amount of pg cause it? Should I tell him to go full vg? Will full vg have any flavor? I guess should he go max vg or the other direction?