I dont put anby faith in the engine dyno simulators. WAY too much is assumed. As far as the whys, the hydraulic cam ramp is much more gentle, because if it was too fast, the hydraulic lifter will collapse under the strain and not lift the valve. Remember they were designed for quiet and no maintenance, not performance. They have been re-designed several ways to help the problems they inherantly have. But a solid lifter can do a better job of quickly and smoothly opening and closing the valves. What you see is the trend of more torque at lower rpms. That's what a solid does over a flat tappet. A roller does the same thing, but mnore so than even the solid flat tappet.
