Mercury Spitfire- Looking for feedback

[Soonertoon]

Ok folks, heres the scoop.

Im re-propping the boat. Currently run a 13 .25 x 15, 3 blade Merc prop on a Merc 90 hp 2 stroke. Need something that will allow the boat to stay hooked up much better under load. Heres my question, I go on the Mercury prop guide, punch in my numbers and it says based on my top speed of 25 m.p.h. ( loaded) at 5800 -6000 rpm , I need a 13.25 x 17 pitch .
I called one of the local boat houses and they tell me I need to go to a 13.8 x 13 pitch. so now, I dont know wich way to go becasue I have no history with a 4 blade screw. the 13 pitch will throw me over the limit on RPM and the 17 will damn sure cut me off at least 600 r.p.m.
Im leaning towards the 15 pitch . does anybody with the same hp motor out here have any historical experience with a spitfire and what pitch did you go from and to, and what was the result and are you happy?
It kills me how many boat dealerships dont know jack shit about props. How the hell you sell something you dont know zip about?

Anyway, if you have knowledge on this issue, please feel free. If you dont, I got all the " Well, now I think" input I need for the day...no offense

[smoker62]

I ran the stock 15 on my 115 . Switched to a 13 Nemesis which is the same prop and it was perfect. You could not get that prop to blow out. Put my rpms at 6150 and gained a mph top speed over the 15. The 15 was running 6100.I also have an 11 I would run when I had a lot of people on board but didnt really need to drop that low. Its a great prop.

[rancherlee]

I've got a spitfire sitting hear waiting for me to take it to the lake and try it. I picked it up to use as a water sports / heavy load prop for my 70hp

[Dusto]

see my signature. I am running a spitfire.