to my understanding they are. I heard from a couple people on another forum that you can rebuild an HP bravo with XR internals. However, those are straight cut gears and you will actually lose 3-4 mph turning them becasue they are harder to turn. But in turn, they are harder to break. I would consider xz gears, since they are an upgrade, but you wont lose the mph.... someone correct me if I am wrong. Mark