humanvr4, there have been several folks in this long thread who have put .91 four strokes in their Twists. I remember asking one to report back after the maiden, but I don't think he ever posted again. You might try a search using the box at the bottom of Part I of this thread. I believe both of the .91's I remember were Magnums which are heavier than your Saito. I don't see a problem myself. I once watched a young pilot flying a Pizazz ( father of the Twist and very similar in weight and size) with a Saito .91. The Saito hauled the Pizazz around very well.