Alright, I am ready to get the holes marked and drilled for the 3 piece spoiler. Obviously the center piece is installed as pictured, and yes I ran several searches, but came up with nothing. Does anyone have measurements for the side piece holes in the quarter panel?

 

Can’t you use the actual piece? I think I would rather use the part to get the measurements than trust some measurements I found on line. What if there off.

If the part has bolts sticking out of it just take some construction paper ,tape two together if you have to and slide it over the bolts punching or cutting holes for them than trim around the edges of the piece giving you a perfect template to work with. Between the piece and the template you should be able to do it.
I used small rubber washers on the bolts before installing my wing to keep water out.
Also your gear ratio would be 2.73 . There is no 2.83

 

Since the piece has bolts that are perpendicular it is impossible to get the same accuracy from laying the piece on the car as using a template would give. I can guess but since I am asking for help, I obviously don't want to guess. If someone who has one installed could lay a piece of paper on the car with one piece removed and make some indicator marks with a photo showing where those marks were made and drew a 1" scale mark and then uploaded said template online for all of us wanting to add said piece it would be hugely beneficial to us all.

I hope I made that clear about the perpendicular bolts. The length of the 3 bolts makes it nearly impossible to accurately mark either the top hole or side holes without the other side not being there. I contemplated cutting the side bolts off and just using body tape but I would rather not do it that way if possible.

 

Hmm re-read your reply and I will try to make my own template the way you describe. I imagine the paper will tear a bit, but its better than drilling and enlarging holes on the car.