I'm new on the site, but I figured I would throw in my practical 2 cents. I have been a jet boat guy for almost 40 years from BFJ's in the 70's and 80's to building my own tunnel. And just about the time I think I have these buggers figured out I find out I don't. The only thing I figured out is to test, test, test.
I have a 21' Carrera with a set back pump, loader, shoe, ride plate, droop, and PD. It runs just under 60mph with just me in the boat and rides awsome over 40, but porpoises under 40 even with the PD. Thats fine at the river, you just go faster than 40. However, the lake I live at now gets very choppy in the main channel on weekends so I spend a fair abount of time cruising at 30. So I figured I would bite the bullet and give up some top speed to fix the porpoise and put on a straight snoot. So go figure, it took care of the low speed porpoise and topped out at 62 with me and my wife in the boat!

So all I can say is test, test, test.