V-20 Outboard HP performance question......

[nymack66]

I have a new VRO pump, however I never use the VRO portion of it from day one, I pre-mix period one less thing to worry about.
I am turning a 13 3/4 x 17 trim all the way down its a stainless prop and from my observation I need to increase to at lease a 13 3/4 x 19 or 20?
I can't be sure just yet since I am yet to set the WOT timing on my new power head I do not allow it to pass 5k rpm and I know it has more to go on the throttle..