There have been some flight reviews here on RCU regarding the VF Edge 540 from individuals who used a 120 on their VF Edge. I have read where the 120 does a fine job on the Edge, but I have also read where some individuals have opted to drop down from the 120 to a 100 or 91 because I am under the impression that they thought the 120 was more than what was needed to make the Plane perform well, and they felt like they could get the same performance and shed a little weight to lighten the wing loading by dropping down within the Manufacturers recommended power range. My Edge is Powered by a Saito 100 with a 15x6 APC, and I feel that it has all the power that this Plane will ever require. I also believe that the Plane will perform well with a 91 4 stroker from all that I have read. It is basically your decision as to what motor you use, but I just wanted to let you know that I don't believe that you would be dissapointed with the performance of a 100 or 91 on this particular Plane, and if you happen to be loooking for a real bargain, the Magnum 91 4stroke is on sale for $149 at Hobby People. The Magnum won't have quite the oomph as the Saito, but I would think it would pull the Plane around nicely, and the Magnums are super nice runners in my opinion.