I've been leaving this thread alone... But, top speed is about aerodynamics, gearing & Hp, more or less in that order.
You can have the gearing, but w/o the HP to push it, you won't achieve top speed. You can have the HP, but with moist ass aero, you won't achieve top speed.
If you have the aero and the HP, top speed is achievable.
Bikes rarely have the aero to achieve top gearing calculated speed.
Speed runs are done twice, once in each direction for an average. Anyone can have an exceptional run once. Getting that great top speed twice over the same measured mile in both directions is a true measure, and a joy.
Can't say I've done that myself.
On my '12 I saw the same 125 GPS indicated, but no more. (NV test track.) I haven't tried on the '15. Feels like it may have a bit more. I don't doubt Sierra1 for a moment.
My tired 'ol FJR would hold 155 all day on level ground. You get used to going fast. Speed just costs money. How fast do you want to go?