Vivi's are stand alone, you may be well advised to get 1 or 2 replacement heads however.
I prefer the 2.8ohm over the 2.5 in the stardusts I use(they are very similar units) on the Provari.
Perhaps get a couple different ohm rated heads to see what works best for you.
Ahhh, ok.
I'll get the pack of 5 cartos to try a sample pack of juice if anyone sells them.