What he said.
And, if you're stacking two rcr123as (16340s) to get 6 volts, you're probably getting a fair bit more than six when they first come off the charger. (I think those are 3.5 or 3.6 volts hot off the charger- soemthing like that, anyway) So in your six volt vape, you're really looking at 7 volts to start.
7 volts into 3 ohms is...16 watts, maybe?? (No calculator handy. But about that.)
I've really never vaped about 12 watts, and even that, I didn't care for. 10ish is pretty ideal for me. Anything about that gets really hot and intense.
Best,
Ande