The air flow through the engine bay is designed to be from the side vents upwards
![](./images/smilies/spacer.gif)
& exiting the vents in the engine cover, introducing another airflow in the opposite direction will have a negative effect.
![](./images/smilies/spacer.gif)
you'll slow the intake rate at the side vents.
![](./images/smilies/spacer.gif)
If you baffle around whatever induction filter you are running
![](./images/smilies/spacer.gif)
& isolate it from the engine bay air you may benefit a NA car but I can't see it making any difference to a turbo.
![](./images/smilies/spacer.gif)
I can see a tsunami of rain getting down them so don't forget to allow drainage.
![](./images/smilies/spacer.gif)
.
![](./images/smilies/spacer.gif)
.
![](./images/smilies/spacer.gif)
.
![](./images/smilies/spacer.gif)