Might try a single twisted coil with one air hole open. So far I've tried a dual coil build (30 ga, 1/16th", ~1 ohm), a single center mounted coil (28 ga, 2.5mm, ~1 ohm), and a single twisted coil (30ga, 1/16th", ~1 ohm).
The twisted coil, with only the second-smallest air hole open, seems to...