Where are you? I am still trying to find my missing speed.

Is this a rhetorical question?

?????
I am 6" below bottom of running surface in front of prop.
The best I can get is 78.5mph with 17% slip.

What props and what RPM? What is your HP?

4 blade 30's
5000rpm
not sure on hp, running a pair of 540's hp500 cam, hp 500 carb, pro top line heads

As a baseline, all 33s had the same x dimension. My previous 33 with HP500 carb motors ran a best of 82.3 with labbed 28 Bravo 4 blades spinning at about 5400. It also ran about the same speed with labbed 30 Bravo 4 blades spinning a little over 5100 rpm as I recall. These were stock motors w/ 470 pshp other than getting rid of the rev limiter.

Without knowing your HP, but based strictly on CIs, I would think you should be able to pull 30s to a little more RPM than than 5000.

Are the props in good shape, blades true and such? Have they been labbed?

What condition is the bottom of the boat in? How much gear and such do you keep on board? Is it possible weight is holding you back?