Lower resistance (ohms) will yield higher power (watts) if the voltage remains constant. So at 3.7v @ 1.5ohms will be 9.1 watts, while 3.7v @ 2.5ohms is 5.5 watts (less power). More power = more vapor.
^ +1 You got to it before me. More watts = more heat and vapor.
A quick chart so you can quickly tell what wattage you can
vape on your
device with the stock Ωcoil heads:
(Atty Ω value across top, voltage setting on left, wattage for setting where the two merge.)
Atty Ω → 1.80---2.40---2.80
3.0-------5.00---3.75---3.21
3.1-------5.34---4.00---3.43
3.2-------5.69---4.27---3.66
3.3-------6.05---4.54---3.89
3.4-------6.42---4.82---4.13
3.5-------6.81---5.10---4.38
3.6-------7.20---5.40---4.63
3.7-------7.61---5.70---4.89
3.8-------8.02---6.02---5.16
3.9-------8.45---6.34---5.43
4.0-------8.89---6.67---5.71
^Volts
You can plainly see that:
The lower the Ωs at the same voltage, the higher the wattage/vapor.
The higher the voltage at the same Ωs, the higher the wattage/vapor.