Whatever prop you use, don't try running it in like an ABC or it won't have a very long life. The first few minutes should be as rich as you can possibly get it then very slowly start leaning it out but still always in a 4 stroke for at least 30 minutes at which time it should be just about to start 2 stroking. Ringed ST's take a long time to fully break in but the time (and fuel) spent is worth it. And use a fuel with plenty of castor for the break in.