Prop size

[ZAK]

I took my v-20 cc out for a cruise the other night with 5 adults and my 3 year old daughter. At WOT the motor reached just under 5200 rpm's and gps said we were going 37 mph. The motor is a 92 150 evinrude and I think the rpm's should be around 5600-5800.My prop is 14.5 by 19 and was thinking about going to a 14.5 by 17.What are your thoughts and am I burning more fuel and putting extra stress on my motor by running my current prop. By running the 17 pitch will I lower my top end ? Thank in advance for your advice.