Since the eGo twist adjusts from 3.2v to 4.8v, and assuming 4v to be the center point, a 2ohm would yield about 8watts. I generally
vape between 7 and 8 watts. I would think you would be safe with anything from 1.8ohms up to 2.8ohms. Realistically, 2 to 2.4 would give you the most room for adjusting. It also depends on pg/vg ratio. High vg tends to take higher watts better. YMMV.