First off, welcome aboard. It's always great to hear from new members.
By stating that you're "Not happy with the holeshot", I assume that this means the time to get on plane is too long. The Max. RPM range for the Mercruiser 5.0 should be 4400 - 4800 RPM's when at Wide Open Throttle (WOT). Where is the RPM at WOT with this prop setup?
A 20P 4-blade prop is pretty agressive. I would bet that this is affecting the hole shot, while optimizing RPM's at cruise speed. I am not a big fan of foils of any kind. The lift to plane the baot should be coming from the hull. A foil adds lift to the boat by lifting the outdrive and puts strain on the drive and transom assembly. This is not where the boat shoudl be getting lift. You would be better off with trim tabs or even smart tabs on a boat this size if time to plane is your concern.
First off, take a look at the max. RPM range @ WOT as per Merc. and then look at what you're actually getting. IF the range is correct look at either getting some tabs, or going down in pitch. a lot has to do with what you want to do. Are you trying to pull a skier? Or just looking for a faster holeshot? Cruising? Economy? Speed?