Hot harsh vapor production has always meant underpowered imo. Like with a soggy wick first thing in the morning or overdripping an
rda. I know it doesn't SOUND right but the coolest your vapor will be is when your coil is converting liquid to vapor at the perfect temp. It's an evaporation process; similar to the one that cools your skin on a breezy day when you sweat. Boiling
juice without complete evaporation can be almost as hot as overpowering but overpowering always brings on a burny taste while underpowering brings on harshness.