Oddly enough, I was running the MAS 9x4 on my P-47's, OS .25FX and mousse can. The plane was a tad slow compared to some of the top of the line planes at the time, but since I managed to keep it at 3lbs, it turned with, or inside, anything. I never did try a 10x4.

Haveing a good cowl on there makes a huge differnece in airspeed, btw.

And don't skimp on the sandpaper steps. The more round the fuse, the lighter and faster the plane. I'd seen a couple that were still very very squared off. They flew, but never quite as well as I think they could have.

Btw, like any combat plane, CG is key as well. Get it back as far as you an manage, and you pick up airspeed and improve turning radius and rate of change of turning radius.