(Try again, as I got logged out after completing my reply to you!)
I have that same spoiler on my Sup, & I wasn't too sure after seeing the photos (imported by Ben Linney at GT-Culture for me). However, I changed my mind when I saw it in the flesh. The photos lend a bit of an optical illusion to it. Wing is not wider than the body, & indeed cannot be for MOT reasons.
However, if you are partial to seeing what's behind you in your rear view mirror, I should point out that the wing obscures the middle distance totally. Easy to lose even a Police car in it; trust me!
The more lairy the body kit, the more that wing blends in with it methinks.