Even with 15kg last year was FZR pretty competitive first couple of races before Z, but last season was a different one from upcoming, yeah. I don't like balast too (who does), but I'm not IGTC admin, so who cares. IMO 20kg is pretty competitive also, in general, I would say. So leave it as it is and prepare for the first race.
Car selection is still up to you, which makes it fair enough.