I really hope you don't have a '97 like the parts you're selling in your sig cause that spoiler wasn't made for your car. :happysad:
If you do in fact have an EG8/EH8, I would use some nail polish that is a contrasting color to the color of your car. Paint the tips of each of the bolts coming out of the bottom of the spoiler. While the paint is still wet, set it carefully on your deck where you are going to mount it. Try very hard not to slide it around and take it off when you have it right.
You will now have dots on your trunk where you need to drill.
hih and I hope you don't have an EK...