I built mine last night, and put the 72 on. This plane was truely designed for this motor. Dropped right in, and it balanced perfectally. No added weight at all. When they designed this plane, they specifically built it for the saito 72.... Anything bigger would be too heavy, and the 72 gives more power then any other engine in it's size. I'm heading out to the field in a few minutes to fly, so I'll let you guys know how it goes later