The marks on my inside trunk lid ('09 model) were either circles or + marks or a circle with a + in it, I'm sorry but I can't remember exactly (dogone k.r.a.f.t. disease anyway) If you are not sure, you can take some fairly wide masking tape and put it on the outside of the lid (line up the spoiler for position first so you have an idea where the mounts will sit) and put a dab of water-based paint or something equally harmless on the mounting posts, and carefully set the spoiler down on the tape. This will leave a mark on the proper spot to drill for the mounting screws. I used tape when driling anyway to prevent the paint on the trunk from chipping. Do a small pilot hole first. I think there are others that have done this install themselves, and maybe their memory of the job is better than mine.