The Focus is going to be a little lacking in power with an os120ax. I have have had several and my current plane is a focus 2. With a os140 RX on a pipe it is little low on omph. I have to keep my verticals shorter than I would like or all i get is a mush over the top. I had an os1.20 ax and while be a great engine it ain't enough to a 10.5 pound plane. Many people ran os160FXs in their focus.