It is attached with the hex nuts inside the trunk (the ones you have already removed), the plastic center clip, and 3M VHB double sided tape. I took mine off of my LT1 and I'm not going to lie; it was awful. Everyone said fishing line would work to cut the tape, but as soon as you get to a screw stud, you cant pull it any further. I VERY CAREFULLY used a long razor blade to cut the tape all the way around the spoiler, then pried the spoiler off with my hands and a plastic squeegee.
Now comes the fun part. Removing all the 3M, high bond tape. My thumbs were sore and raw for a few days afterward. It was not worth it.
Hope this helps.
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