I've built many decently fast boats in my boating life, stern drive v-drive but not a jet. I recognize that a "combination" must work well together. The hull engine and drive.
So what is the best thing to do regarding the jet pump? I know that this is a wide open question but what little things can be done and what big things can be done?
Lets say a small tunnel boat with an honest 900 HP factory stock Berk 12JG pump.
The main objective would be? Pump the absolute most water through the thing?
My gut tells me to install a 9 1/2 impeller, good wear ring, AT bowl a snoot etc. Bolting all of that up will not be enough. What are the basic clearances that need to be held?
And ... what are the optimum intake pressures and outlet pressures? To tune the loader and nozzles?
Those being the big things. What if the stock 12JG pump and stainless B were kept, what would be the little things?