WARNING: This page is about a different car, the 2006 Subaru Outback and 2006 Subaru Legacy. However, it is still accessible from the selected car via links, so may be relevant.
Install in the reverse order of removal.
NOTE:
For the rearmost clip securing the side sill spoiler, install through the end cover.
Fig 1: Identifying Side Sill Spoiler And End Cover