20g is a lot of silicone, IME. I siliconed the handles of my old Prestiges, and added 10g to each frame, and that was a lot.
I currently have 5g in the handle of one of my Pure Storms, and it's more than plenty for damping, which IMO is the primary reason to use it. If you're looking for weight and damping, try (as suggested) fishing weights or something similar along with silicone.