MntSurf

Looking for some help. Just bought a brand new Fi23 with 450 motor and surfing at 5500ft in elevation. It has the high alt prop 16x13. the boat has the all the additional Plug an Play Ballast. This boat will not get to surf speed with two 200lb men and two 120 lb women and full Ballast. I have to dump the two Bow tanks and about 30% of the Ram fill to get to 10.8 MPH. Is this normal?? I would think this boat should be able to surf with full ballast.?? Right?? Should I be looking for a new Prop? I would think the 450 should be plenty of power but its not getting us there....My dealer is NO HELP! Very upsetting! Any info would be much appreciated! Sold my X35 MC to buy this boat. I have Lots of surf experience in other boats, just new to Centurion.