RE: Extreme Flight RC Yak 54 - 74 inch!
Andy - its AUW with an OS160FX is just under 11 lbs. Hence I would say with the SA125 will just about fly her only with hardly much performance for good 3D. The SA125 will turn a 16x6 or even 17x6 giving you about say 13 lbs thrust thereabouts. The OS160 is turning an 18x6 or even up to an 18x10.
Maybe at least a SA150 at the for good 3D fun. I wanna get a YS160 for this baby. Seen one on my pal's CG SU26 and the performance is really nice even with only 5% nitro.