just a cold-air intake filter w/adaptor for my stock intake tube and a WRX cat-back exhaust. Everything else is virtually stock.
I wish it were as simple as a bad MAF sensor, but when plugged in, the car works fine. When I unplug the MAF sensor, the car sputters and stalls. So I'm assuming it's working properly, otherwise the car would sputter and stall all the time.