I had a custom made cable made and that broke in 100 miles.
The solution for me was to retro fit the speedo cable and drive from a pre 2002 V11.
This has worked and has proved reliable.
Guzzi changed to this crap option in 2002 to save money but it has backfired.
In the end I went through 3 cables before I got one that lasted- I did a complete lap of the Irish coast, toured Wales, Scotland, Belgium, Luxembourg, France, Italy, Austria and Germany all with no working speedo so I have a low mileage 1900 mile bike!!!!
Guy