Which props do you have now? If you already posted. I don’t remember.
Sorry this took some time to respond, I spoke to an outboard mechanic (not a Suzuki mech) and showed him pics/vids of my boat running at 4400rpm, clocking 29mph. He told me to disconnect the tie bar and bring the engines parallel, the tip of the nose cone and at the middle of the prop shaft should be same distance apart. Then he told me to extend the tie rod 3/4" to bring the props closer together. I followed his directions to a T, took the boat out for a test run and wouldn't you know it, damn thing jumped up on plane with no ventilation or cavitation, which used to take me almost 1/4 mile before. Have run the boat a few times since making the adjustments and still no issues.
I have since taken more vids and pics of the motor wake and ventilation plate in the water as the boat is running, he told me to extend it another 1/4" to bring the prop washes together a little closer to the stern. He has talked to a few people with similar issues and the Merc Rav4 4x16x17 have also made great difference. As someone said earlier that the Suzuki props are a little softer and flex under heavy load losing some of the cupping.
By no means am I a mech or a prop pro but just putting out there what I did and my experience. I lost pretty much this whole season trying to figure this issue out and if anything I wrote can help someone or give them some direction to go I'm glad I could help.