ACrooks69 - That is not always true. IF the drive is too low than you have to over trim to cavitate ( loosen up ) the prop. My first boat was a Glastron Carlson CVX-18 and the engine was installed at least an inch too low. The cavitation plate was 1/2 inch below the bottom of the pad. ( running surface ) When I trimmed the drive it would actually catch the water and pull the transom down. I raised the engine and drive 2 inches and gained 10 MPH from this modification only. At the time the boat wasn't doing 80 MPH. The reason the engine was mounted so low is the stock risers hit the underside of the engine cover. When I raised the engine I installed aftermarket exhaust.

Tinkerer - The OP and I have the same boat (different year) with the pretty close weight and similar power. I was just telling him not to waste his money on a shorty, because I have already tried it and the results were not worth the investment. Now m old 20ft Searay with 430hp went form 70 to 75 GPS with greatly improved handling when going from a standard Gen 2 Alpha to an Alpha SS. I started out handling limited and ended up power limited. I upgraded boats shortly afterwards so I never got a chance to throw more power at it.

You made a blanket statement " Also a shorty isn't needed till mid 80s. I had one at 72 and all it did was make more problems." That statement is not always true. That was all that I was stating.

Sorry you misunderstood when I said "Our hulls". I was implying we have the same hull. No blanket statement there. And I do agree with you if somebody had said that as a blanket statement.

I am finally going to dip it this weekend to see how it does so i can report back to BBlades for new prop recommendations. When the motor was making 533hp it would run low 70s easy and consistent with an off the shelf B1 and stayed very much planted. No chine walk and never squirrely. I had my risers extended to dry to tip (exhaust and water meet 26" after top of bend in riser and is 3" from actual exit to atmoshpere). Now we are just trying to figure out exactly how much room should be allowed to pass water out of the waterjacketed portion of pipe and still keep system fairly pressurized? Each jumper hose is basically 1" inside diameter so would i need basically 1" worth opening for the water to exit to tail pipe? Keep in mind i know not in one place I'm speaking in terms of AREA between inner (3") and outer 4" in 3/16th or 5/15th holes in the sealed baffling.

Tinkerer you are somewhat correct though. The old motor setup really felt like it maxed out the hull and that was at 72-74gps mph. There were some things over the winter i had need to change and swap out anyway so i decided to go ahead and bump the power up anyway with a compression change, cam and valvetrain change. I'd just like to make what i have work as efficient as it possibly can.