Re: how fast should i be able to go?

[Don]

Bringing the motor (exhaust housing/leg) further away from the transom is what I am saying when I say "trimming out". Try moving that trim rod/pin one notch out (farther away from transom) than it is now. Doing this will raise the bow of the boat out of the water with less friction.
Like Casey says, your helm set up may in fact be too far forward, making it near impossible to do this. You will know when you have trimmed out too far if the engine ventilates excessively, especially on acceleration, and if the boat porpoises (bow slaps up and down at high speeds) excessively.
Again, it would be nice to get an RPM reading at WOT now, to get a better idea if your engine is operating in its designed power band. Look at the transom ID plate, it should give the RPM range at WOT. An engine with a larger pitch prop, like yours, that is lugging, will not perform optimally. Let’s think of this in terms we are all familiar with. Let’s just say I am cruising along in my car at 35mph in fourth gear and suddenly have the need to pass another vehicle. What happens if I leave the gearbox in 4rth gear and stamp on the gas? Exactly, practically nothing. I would have to downshift to 3rd or 2nd gear in order to get the engine RPM up to where it can develop the power needed to effectively pass the other car. Think of propeller pitch as the various gears in your transmission. An over simplification, absolutely. Outboard motors do not have variable pitch propellers (like our auto transmissions). Furthermore, boats do not glide alone easily like autos, there is always a great deal of friction, consider what happens if your engine cuts out completely at WOT, people are tossed around in the boat and could be tossed into the water.