You may try a higher resistance atomizer--I got a Mini Vivi Nova (which may not fit on your setup, I'm too much of a noob to know) and changed the 2.4 head out for the 2.8 one, and got a much, much smoother hit. I don't know how or why it works, or whether it will work for you, but it was life changing for me!
This is an excellent point! My first cartomizers were dual coil (two heating elements in the cartomizer) and low resistance (1.8 ohm), because that is what came in my first cartotanks. I couldn't understand why the flavor of the juices sometimes became burnt and the vapor to be harsh.
Eventually I got around to trying some
single coil cartos in a
standard resistance (2.0 ohm - 2.5 ohm), and they made a WORLD of difference in my vaping experience. From this, I found out that
I prefer a COOLER VAPE. Since making the switch, I've never turned back.
I have a personal theory that the upper coil in a dual coil cartomizer may not always get enough liquid to surround it, being that the punched cartos that we purchase always have the hole near the connector end. The bottom coil is always bathed in juice, but depending upon how well the polyfill wicks the juice (and other factors), the top coil may become dry and burn the surrounding batting to cause a burnt taste.
Below are some pics of a dual coil cartomizer dissected. Note the burned batting that surrounds the heating coils. You can click on the small images to enlarge their size: