I saw on subispeed that they have an AEM CAI for the 2015 WRX. I know it's new, but was anyone able to get their hands on one already? Thoughts?
Also, since I'm a new Subaru owner, I've read that subarus need tunes for various mods. Would this include a CAI installation as well? Or is it okay to run with stock tune?
You pretty much need a tune when making most engine mods on these cars. Currently I do not know of any off the shelf maps (Cobb Access Port) that would work with an AEM intake. If you get your car custom tuned thats' another story.
Mishimoto says it has an intake that works off the stock tune though I would not get it since there would be very little benefits.
Subaru still implements MAF-based fueling (a wire requires X.XX voltage to maintain Y.YY temperature).
I don't know specifics about the 2015 MAF scaling or that of the aftermarket intakes available. As a general rule, I would not alter the MAF housing on a Subaru (or any MAF-fueled vehicle) without being able to calibrate the ECU accordingly.