Good info, thanks.
I fiddled a bit today on a long run back to ramp, seems highest speed I'm seeing is closer to 5800rpm. I haven't checked to see how the motor sits in the water, I'll try that next.
For reference. I have a deep-V aluminum boat powered by a 40hp 2 stroke. Top speed is 25mph via GPS. Fully loaded with two adults I get 23-24mph. I'd say given your rpm's and other factors, your doing fine.