6000 sounds a little high. - Have a look in your manual to see what you should be pulling- probably a little less I would guess. My 90hp Mariner on a 5.4 Searider would pull about 5450 on a 20" Lazer II stainless prop - for just under 40kts. Pulled about the same rpm but less speed on a 19" Aluminium prop.
Suggest that you need to increase your pitch by 1-2". 200rpm per inch is often given as a rule of thumb.
I reckon you should be able to improve on your 30 knots by a few knots - probably at no extra fuel burn.
Secondhand prop(s) are the only way imho to decide what works best - or borrow them from the very helpful members on here!
Bought my stainless Lazer II for the Searider from a member on "Hotribs" - about £100 - was confident I could sell it for about the same if it was no good.
19" Lazer II on the Scorpion came from Pete 7 on here - works well and paid about half new retail cost. Works well and could have sold it for about the same price if no good.
Have fun with the boat and remember - even if a stainless propeller gives no performance advantage - at least it's shiny!
War Shot
