I've read that an individual got a v2.5 Provari to fire a 0.8 ohm coil, but I can not personally confirm that. The main issue with a early model Provari firing low ohms is the 3.5 amp limit kicking in the built-in safe guards in the processor. It will see the low ohms as a short and disable the processor from firing the coil.
The lowest that I have fired my Provari was 1.1 ohm, and I could only do that with 3.1 volts. A Provari will perform best with at least 1.5 ohms, which I build to in my
kayfun Lite Plus rebuildable atomizer.