The panel behind the louvers are not sealed all the way around, not mine anyway.
That allows air to enter or exit the engine compartment. My car is away or I would test it with some wool tufts. I am sure that there isn't very much air going through there, either way.
If you drive a Mangusta in the rain and then open the engine compartment you will find that everything is dry, meaning that there is positive air pressure present.
My car hs a very efficient front air dam, that could affect it.
DICK RUZZIN