you need some down thrust on most models.. the side thrust is to alow the tork of the prop when the engine reves.. If you look at your car you can see it pull to one side when you rev it up.. its the same on model engines. if you put the rong way and too mutch when you open up the throtle it will pull to one side.. i think you need left had thrust.. if you make it so you can ajust it with washers you can find out how thew model performs