Low and High is relative purely to the fuel used tho IMO.
And as we talking about pump fueled road cars, Mike is right.
We not talking about restricted, race fueled, cars.
For the race fuel they run, WRC engines are quite low comp, but theyd go far lower if they didnt have the restrictor, they need to make the most power from the RESTRICTED airflow they got, with the fuel they got, hence the comp they use.
Simple maths that theyd do.

We havent a airflowe restriction.