Looking at the specs and range (never seen this mod), it can go 0.3 to 3 ohm.
Depending on the
tank you plan to use, if you want to be sub-ohming of not. I'd say to go with something in the range of 1 ohm for now. If you want to go lower, I'd say not to go beyond 0.5 at the lowest, and up to 1.5 Ohm, which should provide you with a decent range. over 1.5 Ohm is a matter of taste but I've never found the vape "satisfying" at that point.
And again, depends on the
tank or RDA, and coils type that you use (or plan to).