Dual
coils=more heat(lower ohms), larger coil surface area bigger airflow. Just take one of yours out and you'll get a big difference.
I like to run single
coils myself, even in 'competition type'
rda's but use clapton's or the like which give lots of vapor and flavor almost equivalent to a dual setup because of the large single coil and surface area. You can also try a single parallel build.
For wicking a hot single coil I like to use the Scottish roll.