From my experience with TSTs dont mount them any furtherforward than -2.5 Although it might look like a lot of tip its a long slender rocker and the EST is designed to create a supershort turn radius. If you try and mount further forward you are interfering with the mechanics of the ski and will find it cumbersome.
Think of it like trying to mount a Salomon BBR further forward than factory. It would be even more of a shocker to ski on. The BBR is essentially EST tech just branded differently for a different market