the 15x4w is a great prop for the plane Tony, but the question is "is it good for the saito 82?"
to answer that you must check your RPMs and if there in the 86-9500 range id say great but anythin below that and you do need to prop down a little, say 14x4, but with all that said id like to add that you should never run a 8 pitch on this plane or it will disentigrate in the air from too much speed

and Welcome to the thread, lots of good people here