Converting to daul 38's or even daull 44's on your setup is absolutely NOT worth it. You will see gains but they are minimal; it's not justifiable doing the switch for the amount of time and money you have to spend. Save your money and buy something like a 12/17 skat prop where it is cheap and easy and you get good gains out of it and you won't ever have to screw with it again unless you suck up a rock.
Just from my experience, I've had a ported 61X/62T motor w/ daul44's tuned perfect, and the works. I blew it up ended up with a full 61X motor with pipe, head, and prop. I couldn't be happier with it; the power of that is so close to what I had before that I can't see tossing cash into a motor when it's going to do next to nothing. I mean if you do enough it's gonna make a difference, but working off oem powerplant your not going to see much difference.
