The Minimax was more or less designed around a Rotax 277 engine which has over 2x the displacement of your KTM engine. Remember the old quip attributed to Caroll Shelby? "There ain't no substitute for cubic inches!"

So while you may be able to spin your engine at the speed of heat to get a theoretical hp number, to make the plane go it has to have a propeller of the proper diameter and pitch turning at the proper speed. Otherwise, performance will suffer.