well first thing, The ipow's are amazing batteries. They have a pretty high power output for the ego-twist style they are. I have 3 of them. And my provari has been collecting dust since I bought my first. Very durable aswell. You really need a tank with airflow control for batteries like the ipow. Im not sure if your vivi nova has airflow or not.... Vivi novas have been a waste of money for me in the past. I'm not sure what upgrades they have done to them. For a starting tank, you should really go with a say maybe a kanger aerotank/genitank, or nautilus etc. Trusted tanks. As far as subohm, read up on them, as they are not beginner level mods.
but yeah like said, different juices produce different vapor. Juices with all or high vg will produce the most vapor. PG will produce throat hit. I use a 70vg/30pg coffee flavor from vapage.com. with a 1.8 ohm head in a kanger aerotank mega. About 9-11 watts ( provided the head is clean) will make clouds.
Personally ive noticed the mod and tank have less effect on the amount of vapor vs the actual juice itself.