See how with a tighter pump you gained 6 mph and dropped 400 rpms. A good flowing pump and less wetted, even surface is key to jet boats. You can make a lot of HP but if you can’t transfer it out the pump and you’re plowing through the water, you loose speed.
You’re not too far off 70. You might just need to work with the jet configuration. Some boats like a droop, some might need some wedge to change the angle. Have you tried checking speed at different diverter angles?
An inducer helps to get you out of the hole quicker. Not known to do much for the top end. Some smaller boats notice quite a difference, some don’t.
If you want to just build more HP, tunnels and K-034 and you have good ideas.
For a 70-80 mph jet boat, peak HP is usually 53-5600 rpms. Just depends on the boat and set up. Your impeller will need to match.
What kind of exhaust are you running?
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