This post is a little behind, but it is interesting.
When I got my new job, I drove the Golf for a couple days due to my longer commute, so Chrissy had to drive the Miata to work. Someone tried to run over her so she attempted to use the horn, only to discover it didn't work. Shockingly, the horn did work when I bought the car, so I looked into several possible causes, but thought it might be related to my recent passenger airbag removal. I reattached half of the airbag connector under the dash and the horn was back in action. Great success!