I just finally got around to getting my duckbill spoiler installed on my car and let me tell you how much of a pain it was to actually do this myself. The worse part of this install was trying to remove the old spoiler double sided tape from the car. It took me a couple of weeks to get through this install as I have 2 kids under 2 years old, so that means I get to spend about 2 hours a week on it nightly.
I started with taking off my old spoiler. Worst part of the entire process up front. I already had a sport spoiler so I was going to use the original holes similar to a DIY thread on here for the duckbill. I followed this thread as my guide, but did deviate a bit on some pieces.
DIY AERO JACKET III Wing install (short version) for KaienZ34
I then put some zip ties down into the holes already in the car with some "duck" tape facing up so it would stick to the spoiler when I fitted it to the car. For the most part the molded lines seem to match up so I could drill holes into the spoiler where the zip tie heads lined up and put the original clips into the spoiler.
I then drilled the holes for the clips and epoxied them in place again similar to the DIY for the duckbill spoiler.
The last step for me was to put the spoiler on with 3M double sided tape.
Here is the final look. I had just added EVO-R side blades as well and over all I am finally happy with the look of my car all around with CF accent on the front lip, blades, rear diffuser and spoiler.
For comparison here is my car before the blades and spoiler.