A few years ago I was involved in the development of a twin-engine FADEC equipped aircraft.
We developed a simple logic system linked to the FADECs whereby if one engine was set to its position of transparence (as in a simulated asymmetric approach) the horn would not sound unless the other engine was reduced beyond a predetermined setting. This meant that asymmetric circuits and go-arounds could be undertaken without the horn blaring.
Unfortunately, although the system was completely reliable in all the tests we did, we could not convince the certifying authorities. The aircraft was eventually certified without the system, and cannot be flown asymmetrically without the horn blaring.
I have subsequently been involved in recovering two aircraft that landed wheels up in training incidents...