I'm building a H9 edge right now and just finished the elevator servos. I installed 2 Hitec 545's in the tail. The servos mount about 3/8 of an inch up from the red trim line and the front of the servo is about 1/4" from the leading edge of the stab. There is no wood in this area to mount the servo to. The front of the servo almost touchs the wood in the round cut out area. That's about where you want it to sit. Take a piece of paper and some pencil lead to make a pattern. Hold the paper on the fuse and rub the lead on it to pick up the shape of that open area. Then use that to make a pattern to cut out ply wood. With the 545's in the rear and a OS 1.60 fx in the front the plane balances out perfect with the battery in the spot they show in the plans. The 225 is a good servo but not designed for that kind of use. The gears are to small for the load. That is per a Hitec person that I fly with. They may work for awhile but he gets calls all the time about people using servos not designed for the task and having them fail. Anyways if you where to use the 225 you would move the servo up higher and inline with the leading edge of the wing. Then you would ot have to add any wood. The Saito and Os 160 are with an once of each other just to let you know. The Os is mo power! The OS 1.60 a Perry VP-30 pump Slimline pitts muffler and a mejlik 18x8 prop from Desert Aircraft is the hot set up for this plane. Plus the OS dont drink fuel like the Saito.