There was a topic I never saw anyone comment in the W9 thread:

Quote from Lotsipxes :

I don't think the intake restriction is quite right at the moment. When you have a restrictor plate, the engine has about the same horsepower at low revs. But at high revs, the engine "run out of air" and looses horsepower.

I did a very unscientific test and it felt like the intake restriction was a linear scaling over the power band.

But maybe this will be implemented later.

(http://www.lfsforum.net/showthread.php?t=22757&page=4, middle of the page)

Never tried air restrictions irl, but I think Lotsipxes has a point there.

Any comments? (from people that has tried this irl?)

I know our F3 car was, when we used the F23 restrictor last year, almost unaffected at low revs (nice and driveable, torquey etc) but suffered at high revs as enough air couldn't get through the restrictor...

So yes, it should reduce torque at higher revs, but not so much at lower revs.

Maybe the restriction is not about using proper restrictor plate but just to have direct effect on the power of the engine throughout the entire rev range? "Volatery intake restriction" - so it kinda implies that it is some (veery advanced) way of limiting the airflow to certain percentage at all times.

Basically I'd say it is the power-parameter from LFStweak

EDIT: but of course if the intake restriction (plate) system stays I'd like it to be realistic too. I think it is there just to test the cars with different power figures to balance the classes

normal low end and cut off high end seems consistant with restrictors that i have seen, as with the vipers in scca they have a ton of low end, but on the high speed straights they have to carry long gears to keep revs down, beyond the fact high revs will destroy the engine

Quote from Hyperactive :

Maybe the restriction is not about using proper restrictor plate but just to have direct effect on the power of the engine throughout the entire rev range? "Volatery intake restriction" - so it kinda implies that it is some (veery advanced) way of limiting the airflow to certain percentage at all times.

Basically I'd say it is the power-parameter from LFStweak

EDIT: but of course if the intake restriction (plate) system stays I'd like it to be realistic too. I think it is there just to test the cars with different power figures to balance the classes

Maybe it is just a naming problem? What if it were called "competition ECU adjustment" instead of "intake restriction"? This would imply something that limited power across the spectrum instead of what an air restrictor would normally do.