U-Can-Do what motor do you really need
Hey man.... I flew the one on the 3dbatix website. Its got a 91, and would EASILY take a 120!!! The only way that it would screw up your 3D is if you made the plane too nose heavy!!! The weight wouldn't hurt it. The wing loading is sooo low, that if you brought it up a few oz./sq. ft., you wouldn't even notice.
And just a suggestion...........NEVER listen to the GP manual for tips on 3D flying.