Have you actually looked at an intake. If there was no benefit for ram air why have it to start with. When you select an open by pass you are directing the airflow so it dose not enter the engine. In some cases it flow by and in others it also has a cane that comes down.
Preformance loose with out ANY forward movement on a b200 is around 40 Ibs. Close the vane it increase 40 lbs.
but clearly pilots no more than the people that make and fix em.
And there fore it's all magic. Tq can be measured in psi , lbs or even %. But it is comes from the same spot on the prg.
But the fact is ope the by pass and you will loose engine Tq. And if you are itt limited that's your job lot. You can't increase power.