[fabrio.]

both valve create an restriction flow.

The problem came from the throttle isnt' full open.
Power is needed to create flow, and this power is loss.
The valve (in the head) create its power loss, but at certain RPM the acustic effects on intake runners (or exaust) minimize this one.
So, at the full throttle, in the Otto engines, the power loss caused from the throttle it is at the minimum.
Only when the throttle it is at the minimum or partialized the its powerloss is bigger.
A way to eliminate the throttle losses is to eliminate the throttle
In this case, the engine power can be regulated from an valve lift and timing electronic controlled system.
This one, permit to create required torque limiting air inlet in the combustion chamber whitout a lot of pumping losses symply, because the acusti effect (resonance and pulse effect) has calibratet in order at an lower pumping losses.