Just got my Wrx back from the bodyshop yesterday...I decided to post this because when I ask the dealer where i purchased to car from they said that the STI and WRX use the same Trunk lid, So the Wrx spoiler can be swapped with the STI Wing. They did warn me that there might be a slight issue to the bolt holes.
When the bodyshop removed the factory spoiler, they found a total of 14 holes!!!! Which 11 where on the center of the trunk lid.
After spending an additional $800 to fill,grind, sand, paint, polish and mount the new wing, Heres how it came out....
I post pictures of my car when it was in the bodyshop and all the work needed to install the wing.