Mine's running 15/39 too, for curvy rides ... in Belgium !!!
From time to time, I have to visit friends Ducati fans, located about 130 kms from home. Roads have perfect asphalt but are very very ... straight. I agree that's not fun, but I enjoy this travel. In such a situation, I change the gearing 15/36 ---> 120 kph at 4000 tr/mn. Thus, the engine rev. in association with Termi sounds and tows like a railway engine ... means pretty bewitching .......
Don't laugh at me, life is a test ... 888 spirit too !!!