Thanks for your answers RIB- Teccie.
So I raised the engine this morning one hole. It is now at the second highest setting.
Changed the prop to the Quicksilver Vengeance 13 x 18. Into the water and out testing. The tach showed 53-5400 rpm at WOT, speed 41 knots. Fast hole-shot, almost no chine-walk, good grip in turns. I gained 1/2 knot and 50-100 rpm by raising the engine (same prop, driven in similar conditions on monday)
Back to the harbour and on with the old 21 inch alu. WOT 53-5400 rpm, speed 42,5 - 43 knots with some chine-walk and loosing grip in turns if I dont trim in the enine in turns.
So the search for a perfect prop continues next spring as we are slowly prepearing for winter over here