Just adding a note for this how to thread on replacing the cabin air filter since I just did mine. The two screws did not release when unscrewed so I had to pinch the plastic pins together to remove them. For the one behind the battery I used some needle nose pliers.
Also, the pin that fits at the edge of the hood was broken or I broke it pulling up so be careful there. The car has 15,000 miles on it and had quite a bit of dirt/dust in it. Here is the link to the how-to from a previous poster( Should be a sticky).
http://forums.stangnet.com/784797-2006-mustang-gt-cabin-air-filter.html
Also, the pin that fits at the edge of the hood was broken or I broke it pulling up so be careful there. The car has 15,000 miles on it and had quite a bit of dirt/dust in it. Here is the link to the how-to from a previous poster( Should be a sticky).
http://forums.stangnet.com/784797-2006-mustang-gt-cabin-air-filter.html