Hey Sully!
First off, let's talk about realistic expectations for a 17 ft. aluminum boat with a 40 HP outboard. Assuming that you have power trim and tilt, you can realistically expect to get about 32 MPH out of it under ideal conditions and two people in the boat. Maybe a tiny bit more, but only under perfect conditions.
Now, regarding your props, I'm willing to bet there is a number stamped somewhere on that one prop, but it might be hidden under paint or something. Who knows? But, with regard to the number on that other prop, 38x14 doesn't sound right to me. The 14 does, but the 38 doesn't make sense. The 14 should be the pitch and the other number should be the diameter. Can you check those numbers again and make sure of what they are?
Also, if you have manual trim, and not power trim, you will never get optimal top speed out of the boat, since your outboard will be in a fixed position that will be a compromise between good holeshot and top end speed.
You can also try playing with the height of your outboard by moving it to different holes. Moving it up one set of holes will usually give you pretty drastic changes, but not always positive changes. But be careful not to raise it too high so you don't end up losing water pressure.
Lots to consider here. But remember to keep it realistic in your expectations because MPH cost a lot for a little return on your spend