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Did a quick search, but couldn't find an answer. Why is the airbox open with a gasket on top? Is there some sort of channel on the underside of the hood that directs air into it?
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Last I remember it was said to give more sound/whoosh. The gasket seals against the underneath of the hood. This was witnessed on a display FoRS at SEMA. I speculate that air could be directed to the opening given the brake ducts in the front spoiler. Can't confirm since I haven't seen under the hood when I've seen a FoRS in person. Hood's always closed.


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The pictures in the Promo Pack don't show the underside of the hood but there is a close-up of the airbox...
 

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Aerodynamically, you don't want a hood with an open vent because of Bernoulli's_principle. Instead of providing more air an open vent on the hood would create lower pressure and actually suck air out.

So maybe the open vent under the hood actually does provide a freer air flow into the engine as others have said, for a better sound.


YMMV,

MidCow3
 

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My guess is that there could be some sort of under hood routing going to it. Sort of like the way subaru got rid of the hood scoops on the forester and just route the air from the grill to the intercooler. Plus it would definitely allow more intake noise.
 

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Attention-to-detail nuggets include the way the air intake is sealed at the top by the bonnet, meaning that when the new RS is put on a dyno with the bonnet up, the intake opening is much larger — compensating for the missing charge effect you get when the car is in motion, ensuring it breathes properly when revved up but stationary. This stuff matters to fast Ford fans, and it apparently matters to the team that built the RS, too.
Source

So there we go. For dyno purposes.
 

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So the green filter is just better flowing? Any other advantages like being cheaper than OEM?
The Green Filter is better flowing, but not cheaper. An oem filter for the ST is $15 or so. Green Filter is $60. The cleaning kit is $15. So after 5 cleanings rather than replacing stock filters I guess it's cheaper. At that point you're at like 100k miles.

It does sound better though ;)
 

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