Spark plugs said I needed a new air filter. I've found one at a local store and am about to go pick it up, but double-checking made me uncertain.
What I've got is a big rectangular filter which Google informs me is a cabin air filter. I also seem to recall a tutorial for installing a round air filter, but I can't find information on it at the moment.

Is there really two air filters on the non-turbo models, or does the cabin air filter serve double duty?
I would appreciate a quick answer, since the store closes in an hour. &thanks for any helpful replies. =)

Edit: I've figured it out on my own. Apparently there's a big black box on top of the engine with "Air filter" written on it in massive capital letters. So that's the lesson of the day. Coffee first, repairs second.

 

There is the one filter under the Air Filter black box that all 850s have. It's the one you found for the engine. Some of the 850s have a cabin air filter in which case they would have two.
To get to the cabin air filter you have to pull up the cover that is under the wipers on the passenger side.