My guess 3-5 mph on top end!!
I hope you are right, but I think it might take some prop work before I see those gains. I have been running numbers in the prop slip calculator and it's just not showing those kind of numbers. I think the Raker is not going to be enough prop in regards to pitch, it is a 24, which is what many have told me works on most 175hp engines, especially if my boat likes the 27 Shooter. I think I'll need to have it worked to a 25. Here are the slip numbers I got:
Shooter 27p: 65mph (gps) @ 5600rpm = 16% slip which I believe because of how beat up it is
Raker 24p: 67mph @ 5600 = 2% slip hahahahaha, impossible.