Don't worry, your techno-babbel is pretty clear.
Now, for the top-speed of the RedJet4. I wouldn't worry about those few knots, ACR. All depands on more conditions then hull and engine alone. If the water is calm, you will get better speeds. If the air is cool, the engine will deliver (slightly) more HP then when the air is warm. And so on, and so on.
With these kind of fast ships, its fairly easy to gain or lose a few knots deu to weather and water conditions.
So, i wouldn't call this a glitch or bug, rather then a positiv intrepetation of the RedJet4.