ON3P recommends mounting them at recommended, so -4.5ish, or within a +/- 2cm range. So going forward 2cm and mount at -2.5 could be the ticket for what you are after.
If you want to mount them more centered than that, then you could perhaps reconsider the model of choice and get Magnus96s or 102s instead.
yeah, you'll get a lot of "I mounted my skis at +alot/centered and it was fine/brilliant there" type comments, but the flex profile and sidecut of a ski are both designed around a specific mount point range and will work best there. If you are going to deviate significantly from that range (like center mounting a pair of Jeffreys or Kartels) then you are prob on the wrong ski, regardless of what X number of people commenting based on experiences from completely different designs/skis will tell you
So my recommendation is go -2.5 from center to make them even better for park skiing, do not overthink it - they will be brilliant there both in the park and around the mountain