Many thanks for the detailed information
Craig8! What you mentioned is about what I expected, given the price point. And that's funny about instructions--I specifically asked them that question and they said instructions are included.
I also read that review about the lady who lost her spoiler on the highway and they claimed it was poor installation so that concerned me. I almost ordered some 3M tape but I'm glad I didn't since you say there would be a gap. I bet some
Amazing Goop would work well for this application. I used that stuff to install screens to protect the radiator and intercooler on a different car and it's solid after almost 2 years and the car has seen a few track days.