Looking for ACME prop data

[rmlsll]

New to me, 18x23x4 ACME props on my 2004 340 sundancer W/ 8.1 V-drives. At WOT I'm getting maybe 4300 rpm's / 63 GPH / 38 MPH. and at 3500 rpm's I'm getting 40 GPH / 30 MPH. My understanding is that there are several 8.1 v-drives with 23 pitch ACME's that are getting substantially better numbers than me. I changed plugs and wires with no change. I guess a pitch reduction is next, but why is my boat so much different ? WOT numbers are 1/2 gas, 1/2 water, 4 people.
Anybody have numbers too share off there 340 ?

 

[In Two Deep]

I tend to run at 3600 to 3800 rpm 30 gal/hr 23 to 25 its depending on the seas I have no idea what my prop pitch is.