I will say there i notice a differance between the ego 3.2 and true 3.7-4.2.. with LR. 18640 bat mod will stay at above 4 for a while.
3.2V, 1.5 Ohms = 6.8 Watts (Standard 510/eGo with LR atty)
3.7V, 1.5 Ohms= 9.1 Watts (Standard 3.7V Mod, LR atty),
4.2v, 1.5 ohms=11.7watts (full charge)
50v 2.5 Ohms= 10.0 Watts (5VMod, Std Atty).
I only point this out because i like smaller mods. just thought it was worth mentioning.