Vivi Nova's are fantastic, but like anything else, depending on the PG/VG ratio of your juice, sometimes take some tinkering to get them just right. Most of the time, it's simply cutting back the silicon cap that sits right above the wick to allow for easier flow of thicker juices to the coil. Be careful not to cut it back too far, or you could flood it. I'm talking a fraction of a mm at a time, until it's just right.
