The install kit includes bolts for securing the mounting plate to studs as well as hardware for mounting to the drywall.
The strongest method is securing the plate directly to the studs. In my case, the stud locations only allowed me to use one of the two studs. The right side of the microwave (the heavier side, by the way) is secured with three screws into the stud while the left side is secured with three drywall butterfly bolts.
As I was deciding which cabinets to order I was worried about the final height of the microwave. I'm around 6' 3" and didn't want the microwave blocking my view of the stove top because of it being placed too low, so I went with a slightly shorter cabinet above the stove than was recommended. After the cabinet was installed I could determine what size spacer would be best used between the cabinet and microwave. In my case, about 4" was ideal. 4" was also the height of the toe-kicks that I got for the lower cabinets.
A spacer was made with the toe-kick which works nicely to space the microwave where I want it. I need to do a little custom work for the mounting bolts now that go through the cabinet, because the bolts aren't made to handle anything longer than a 3" spacer. I'll go with longer bolts if I can find 'em.
