Silica does not wick nearly as well as cotton. There are several threads here on using cotton. Even if you don't want to completely rebuild your heads, you could remove the silica wicks when new (or even after using) and replace with either:
1. organic cotton balls (probably good idea to boil 20 min and dry before using so boil several balls so you don't have to do this but rarely)
2. Walmart Peaches & Cream brand Ecru (color) 100% cotton. It is always recommended to boil formed cotton before using (like yarn) because of additives used to help it keep its form. 20min minimum, then let dry.
3. CVS (or the like) sterilized rolled cotton. (People claim this needs no boiling.)
Which ever method, you pull off enough (dried) cotton to roll between your fingers into a wick, and thread it through the coil. (With the yarn just unravel the strands and use two or so... don't use yarn myself so maybe someone else can chime in with how many strands to use.) The thickness should just be enough that you start to feel resistance pulling it through the coil. It will swell when it gets wet. Trim both ends and prime with a drop of juice right on top of the coil. Put head back together and let the mod sit a few minutes so the cotton has time to soak up the juice.
The first 3 or 4 hits will taste like cotton so don't inhale if you don't want, but after that the cotton taste goes away and all you get is flavor. Much more so than silica, and it wicks better, so you won't get dry hits as long as there is juice in your tank.
You may or may not need a flavor wick (can also be made of cotton), per your juice and coil type. If you require a flavor wick and don't use one, you might get gurgling or leaking. But not everyone needs them and if you don't need it and use one, you'll get less vapor and reduced performance. Some experimenting might be necessary. But in the long run, it's totally worth it, imo.
NOTE: You cannot dry burn cotton.