just a little bit of advise if you decide to go fly without the cowl.. RECHECK YOUR CG, i tried doing that and it ended up so tail heavy that i almost couldn't get it down in once piece.
So sturtz I know that your using the 91 fx but, witht he 15x4 do you think the plane flys to slow? I kind of like a speedier plane but, i could definatly use some downline breaking and probally a shorter final. With my saito im tempted to fly a 16x4 but, i dont know.