I know you were only testing out the top speed, so if you don't ride at those speeds on a regular basis, you don't need a fork brace.
I ride my 955 up to 100mph, and that's fast enough. It's stable at those speeds. And more to the point, it feels like you shouldn't be riding it any faster than that. Some bikes are designed to be ridden at speed, some aren't. Just think about what the bike is actually designed for