Better pads and stainless lines make a big difference. I went a little farther and have Subaru 4pot front calipers, stainless lines, Axxis Ultimate pads and dba slotted rotors front and back. I really like the improvement in brake feel, the stock brakes don't have very good feedback.

Steve

 

I would suggest pads, lines, and a good quality brake fluid. These things will make a difference and will not cost an arm and a leg.

If you want to go a bit further, then you have options of big brake kits like the Subaru 4-pots, Wilwoods, StopTechs, Brembos, etc. Obviously the larger the brake upgrade the more money it is going to cost. Also going this far could require you to upgrade wheels from the stock WRX wheels.

 

Pads- I did pads first (porterfield R4-S) and I liked them, but I should have done fluid/ss lines first

Rotors- Stock rotors are fine unless you start to do track day or hard driving. I've grooved the crap out of mine, and have DBA gold slotted/grooved on the way. No cross-drilled. I'm afraid of cracking... but cross-drilled look NICE!

Calipers- I have the perrin/willwood's on the way. They fit under the stock 16" wheels, and have a 4-pot design. If you have 17's or want ultimate performance, get 17's and the Stoptech Big Brake Kit.

Lines-Great upgrade. should be done first. get the Goodridge lines with a stock set-up

Fluid-You'll have to replace this when you do the lines, so wait to do it all at once. You can get the blue stuff they sell from Cobb (good) or you can splurge on Motul RBF600. You can find the Motul stuff at a cycle shop, or PDM Racing. I went with the Motul because I could buy it local and it's used in professional racing. I'm like that.

If you are interested in my humble opinion (and even if you're not you're going to get it ) then I would say get SS-lines, fluid (blue stuff or any DOT4 fluid), and some decent street pads (Hawk and Porterfield come to mind). If your wife races then go crazy and get the 17's and Stoptech.
-Happy Driving

 

fwiw, im running ss lines,motul fluid and hawk hps pads.. and honestly the stock setup felt almost the same in day to day driving maybe even a little better.. im also running azenis.. just my 2 cents..
--bobby

 

So I guess most people are recommending a better brake fluid (how about Motul DOT 5.1) and SS lines (GoodRidge) first.. and then pads? Thanks...

 

What's your wife complaining about: stopping distance or brake feel? If it's stopping distance, your best bet is better tires first then better pads. Doesn't matter how good your brakes are if your tires suck. I've been happy with the Ultimates I've put on other cars. If she doesn't like the pedal feel, then upgrading the brake lines as well as pads will change this. Upgrading the brake fluid probably won't help much unless it is either old or else has been boiled due to excessive braking.