42 gps was on s calm morning no wind no chop. 5900 rpms. Not sure if I remember correctly cruising at 30 mph around 4000 rpms.
as for the wandering at idle speed its the nature of the beast.
I have a 2013 pg175. Combo
I run a 17 pitch solas 4 blade
Ive hit 42 gps with two of us and gear calm water. Generally with gas people and gear i get 39-40 gps @ 5700 rpm decent holeshot and no sidespray.
Quicksilver 13.25 17p ill run a 19 p when there only me and one other in the boat i also have a quicksilver 18p stainless but I haven’t run it much yet. It sounds like the newer model proguide v175 would run better with the 150 fourstroke
The way i do it is to start out with the trim all the way down hit the throttle wo once the boat is on plane trim up gradually till i hit the sweet spot. With a 17 p prop i can trim all the way up and run 40 mph gps
Some years ago i had a similar problem with a 90 4 stroke had trouble getting on plane. Took it in and it turned out to be a timing issue totally different boat once that was fixed
17 or 19p three blade is all ive used with no issues and no problem getting to the 6000 rpm area 40 mph. I also upgraded to the 80 lb 60” terrova best upgrade ive done to it.
2015 175 pro combo. Love the boat no problems. Only thing I would change is I wouldn’t have gotten the combo. Nothing wrong with it I just don’t need it.
My full throttle rpm range is 6400 rpm right now im running a 19p 3 blade prop getting jus about 6000 rpms 39 mph with 3 adults 1child gear and a full tank of gas
Its a 2013 with the standard gear box. I can run a 17p prop at full tilt 6200 rpm 40 mph only time i get blow out is on a heavy turn. I can run full tilt with no porpoising.