[76Red18]

I just purchased a new prop for my 18 last week. The motor is a 99 Johnson 150 so the combo isn't the same but I'll give you the info just the same. My old prop was a SST 15 x 15 and worked well until it spun the hub last time out. It would give me 40 - 42 @ 5400 rpm and a good cruise of 30 or so.
After hearing all the good about 4 blades and forum member EggSuckingDog praising his Stiletto 3 blade, I decided on a Stiletto Bay Pro 3, 14 1/4 x 15. Have to say I love it. In anticipation of that prop's ability to run close to the surface, I raised the motor all the way up. The prop holds the water to almost full trim but I need to lower the moter one hole to get the water pickups down a little. It starts to get hot at full throttle full trim. On the short wide open run, I saw 44 @ 5500 rpm. Thats the fastest the boat has gone and that was even with a full load.
I'll get some better numbers the next time out. I would also say it looks like you need a 17 pitch.