I have a new to me 2004 Ranger 521 DC with an 04 250xs with a 6" manual jackplate. I'm getting similar speed with a somewhat dinged up 27 Tempest (5100+/ RPM - 65 MPH) with a new 25 Fury @ 5400 +/- RPM - 65 MPH. I've been told this setting should do 72-74, but I don't think I've ever hit 68...

I haven't measured the plate height yet, but I've played with it from the factory setting down 1", and back up 3/4", yet minimal change (best 1/4 below factory setting). Does anyone know the perfect prop, pitch, jackplate setting and plug hole diameter (in prop)?

New plugs, Quick Kleen treated, always 91-93 octane, just replaced fuel lines (almost 30% clogged with the old liner - but little different top end noticed = much better hole shot), new temp sensor, I've run a couple cans of Sea Foam through both tanks and no significant improvements. I'm tired of dumping money into the boat with the hopes it'll make it hit 70+.. All advice appreciated as I'm tired of throwing money away.