Thanks guys, that is what I wanted to know. I had thought the Saito .56 might be too much engine for a 630 Sq. In. sized plane, but there I go thinking again. What about the inverted mounting versus the side mount, does it matter that much? I'm just asking as I don't know, and from what I have read here some say it doesn't matter and so on. My Saito .40 is on a profile and it runs fine. Plumbing the fuel lines would be a problem in a built up fuse, as this is not a control line version engine, its merely has the insert in the carb with the nylon choke screw. It runs fine. This is basically all experiance I have with 4 strokes, other than an OS .26 on a Ringmaster and that one had the carb replaced with a regular venturi, by Bob Zambelli. It runs really good, so far my experiance has been good, but not with a bigger plane, or with the engine in a built up airframe. I've run 2 strokes all the time, so forgetting what I know about them, really shouldn't be that hard........but, some good ideas and help would be greatly appreaciated.