As i was surfing youtube I came across this video! I know A LOT of people have complained about how our stock HU sucks. It worked in my 2011 WRX. I hope this helps some of you! !
I tried this in my 09 wrx, and it worked except for turning the loudness on. Sedan, wagon, and through mode are all there tho. I figured I'd leave a comment since the YouTube video says 2010 and up, it's actually 08+. Cheers!!
I made a post on this a while back. It has a little more detail on what all the different settings actually are. http://mnsubaru.com/threads/disabling-changing-the-eq-on-the-2011-head-unit.42771/
