6 MONTH UPDATE: So far so good. Running really well, without throwing any CELs, no hitching in acceleration (except maybe from CAI snorkeling in water). I think it was $300 well spent (speaking as someone who doesn't wrench on his own cars).
Here's a pic of the car on 2/18/12 on the way home from
AWOL LAN 19. Just had the car washed the previous morning, but it snowed on the way up. We had all our computers in the trunk, and probably 800+ pounds worth of dudes in the car (well, less because I was taking pic). Rear end was sagging a bit. The wheels are -1" (17") cheap alloys with Blizzaks.
Here's a pic from a week ago after an oil/filter service at the Mazda dealer (Rosen Mazda, in Waukegan, IL). If it isn't freezing, they wash your car for you. Combined with $15 off coupons and their "buy 4 get 1 free" offer, ends up being around $20 each time for oil/filter/carwash. Took the pic to remind me what a clean car looks like.