I think the 5.7 is too small for the 22 MXZ. If the boat you are demoing has the 5.7, I suggest loading it up with ballast and people, as it will be used. For surfing, thats MLS full + 750's in the rear and a 400 in the walk way. The 7-10 people and see ho it goes. At a minimum, this setup needs the upgraded prop, but even the larger engines will benefit from a prop change. The pre-surfgate MXZ surf wave was, well, nothing to write home about, but the post surfgate with the spray-gate fix, is much better.