The OEM cage is a really good design to start off with. If you need to, you can put in Boysen reed petals as an upgrade to stock ones. As far as the pyramid cage goes, I had one on my bike & sold it to MHR for $5.00. It was just too restrictive. However, MHR says that they can be opened up for better flow.
The testing that I have done with reeds says that the basic design of the pyramid is just the opposite of what it should be. Engines wants as much flow area as possible at low petal lift. This means that we are looking for reed assemblies that maximize the flow area near the tip of the petal where the petal tension is minimal and not at full petal lift.