I agree, just want to expand a bit: all of the toppers you mentioned have smallish coils. Factory made coils are very limited (IMO) in how much power you can give them before getting a burnt taste. The kayfun is obviously dependent on how you build it but with the chimney being kinda small you can only get so much coil in there. That's where drippers come in. I'm not one of those "you must drip" kinda vapers but if you are comfortable building you should have one for trying new flavors at least. My point is most drippers (not all) have considerably more room to build a coil on allowing you to find the balance you want of coil, air flow etc. It is also possible that liquid just can't handle the power.
I was nodding my head enthusiastically until that last sentence!
Truth is, the e-liquid doesn't have little watt-meters floating around in it. What matters to the e-liquid is the temperature.
The coil is heated by the current flowing through it, but it's cooled by the e-liquid; as the liquid vaporizes, it pulls heat out of the wire.
If too much liquid is on the coil, it won't heat up well, and you'll get a lousy vape. If there's too little liquid, the coil doesn't get cooled off enough, and it therefore will get to a high enough temperature to burn the liquid.
If you want to go from a good-tasting vape at 8 watts to a good-tasting vape at 16 watts, you either have to double the surface area of your coil, or else get the e-liquid to flow onto the coil twice as fast. A better wick in the small heads you are using might be able to increase the liquid flow enough to do the job, but as CoolBreeze said, you don't have much room to work with.
