I purchased a 3D carbon used from Ebay. It was in "gotta have it green", but my son working as a painter in a body shop easily got it to race red (my color). The fit/finish is fantastic. Not sure what year it was made, but there are no issues with any buldging. Mine also did not have any tape; it had the factory mounting studs, and no drilling was required. To date, it is on perfect, no gaps, so I'm assuming the 3M tape is not needed.
As to the gurney flaps, it is molded in, at least on mine, so it is not removable. The stock Ford types allow you to remove the gurney flap and replace it with the second one. Ford made two, one with a lower flap for different track setups.
My son masked off this flap and painted it black. Unless you are right on top of it to see it is molded in (on the 3D Carbon I have), you could not tell it is not the real deal. Then again, I do not track my Mustang, so being able to change the gurney flap is not an issue with me.
I'm a huge fan of buying Ford OEM type parts, but in this rare case, I got the 3D carbon for 90 bucks shipped! And the paint job was free. Great to have a son as a auto paint tech.
It is better to keep your mouth closed and let people think you are a fool than to open it and remove all doubt.