Thanks to neverendingmods for "discovering" this tidbit! The 04 WRX made a significant improvement in the sway bar mounts (what mounts your sway bar to the chassis). This is a good mod for anyone running bigger sway bars or even oe, as it's much beefier. You can get the entire upgrade for ~ $30- this includes two mounts, two U brackets and two bolts.
Here's some pics of the "old" vs the new mounts: