Sorry - I wasn't really considering the OEM one (or RPM's "
Performance Spoiler," which I was told was the same as the OEM one, and which the description indicates is the same size as OEM), so I don't know the answer to this question with 100% certainty.
However, if you look at the pictures on RPM's website, both the Performance/OEM and the Performance Plus seem to be the same width. Also, I suggest you watch the videos for both products (under the "Description" tab), which may give you a better idea of the size difference between the Performance/OEM and Performance Plus, as well as between the rounded Performance Plus v. the V-style Performance Plus.
In the installation videos, it appears that there is only one tab for the Performance/OEM spoiler, which suggests (to me), that it attaches to the trunk via one piece of 3M tape. For the video on the Performance Plus, there are two tabs, which suggests there are two pieces of 3M tape. The video also states the contact points for the Performance Plus are both on the top of the trunk (horizontal plane), and the back of the trunk (vertical plane).
To me, this suggests, the Performance Plus has extra surface area to stick onto. However, that's just my educated guess, so don't hold me to that.