First thing check the bottom. Make sure it does not have a hook in it. If you do not know how have someone who does check it. It can cost you 3-5 MPH. Fountains are bad to have this problem, as others do also, because the hulls take a while to cure out. Setting on a trailer or boat lift while it cures will cause a hook. Not so prone after a year of so. My 38 ran 114 when new, one later it ran 110. Had the factory check it and it had a hook. Fixed it and it now runs like it is supposed to.

That is the best input all together. We try to think otherwise, but the most $ wins. But I trully love the father/son relationship. I'm jealous ( my Dad is no longer with us )

What is the critical area to check out here, from the transom up to the first step?

Use a long straight edge and place it at several places on the bottom running surface. If you can see light between the front edge and the rear it has a hook. Doesn't take much to suck the boat down and not let it get up and run. Measure from rear toward the front. Mostly extreme bottom and out to the first strake. WHere the bunks of the trailer ride.