Attache K2, Everest or Peak 4 to your existing groundbox and you will get a obvious impact.
We normaly use wooden caps on our binding posts. Wood is totally neutral isolator.
Add nothing and deduct nothing, so in that sense it is the perfect material.
By use this fact and add a mix of metals that are dia, para and ferromagnetic to the bindingpost you change the performance in the whole box. Not only on the used bindingpost.
It´s the whole total mix in the box that changes when adding this metals.
This means that you as user can fine tune and upgrade the box so it´s working optimal for you.
For more tip about upgrading, please take a look at Magma Tungsten