Take it from someone who has done it. He will NOT LIKE the 4.2 on this plane.
I had one, hated it, sluggish in the snaps. never could get it into a real flat spin, Harriers were a joke, then changed out the engine to a 3.2. ALL THE DIFFERENCE in the world. Loved the plane. As Tom and many others will tell you (just do a search) the plane will not take anything larger than a 3.2.