I run both there head and cylinder studs. They are a good kit. Since the head studs have allen heads on them you don't have to remove the entire enging to install the head. There isn't enough room to slide the head over the studs with the engine in the frame. You just install the studs with an allen wrench like regular bolts. Bottem them outn and snug them down. The put the nuts on and torque them to 40ft lbs. I also put anti sieze on the threads that screw into the cylinder. That way they will be easier to remove later on.
The studs that go from the cases to the cylinder do not have allen head scockets. So you have to use doubled up nuts. There is enough room to slide the cylinder over the installed studs. I also put anti sieze on the case end of the studs.
I don't know at what point / hp level you need studs, but it can't hurt to have them.