I did the H-6 brake upgrade this weekend on my 04 wagon. It was a 1-2-3 easy operation. I chose to bend the dust shield back, so I warn all others to really make sure it is bent 100% out of the way. My first test drive resulted in lots of rubbing. I had to take the left side all apart again and massage the dust shield with a hammer.
For the price, the H-6 upgrade is as good as it gets for a WRX. FYI, the pad kit has everything you need.....except anti-squeal compound. You'd think they could put in 25 cents worth of that stuff for the price.