The open area should face the firewall. Here's a picture of a stock air cleaner on a 216. Look closely and you will see a raised portion in front of the copper mesh in the front only. The mesh is exposed toward the firewall. In fact if you zoom in on that raised portion, you will find that the word "front" is stamped into it to tell you how to install it.
![[Linked Image from i100.photobucket.com]](http://i100.photobucket.com/albums/m11/48fleetline/vcca/ca54e93c-4881-4048-9bac-770042fbc7d0_zpsb9ad5b2a.jpg)
So that's just my opinion on how your air cleaner should be mounted. I've been known to be wrong on many occasions

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It's your car and you should have it the way you like it
