77lb springs. That's pretty high, but based on your weight, passenger frequency, and luggage requirements it will be tailored to you.
My Wilber's are 65lbs, but I'm on the lighter side of R3 owners, never carry a pillion and my bikes allergic to luggage so they work perfectly.
The trick is matching the damping rate to the spring rates, which they no doubt did, resulting in what is im sure, a smoother yet firmer ride than stock, that soaks up bumps better while using less travel to do so.
The suspension bible basically suggests having as little damping as possible while maintaining the damping required to control the spring. This results in a bike that will move up and down, soak bumps, but doesn't wallow in turns. That's exactly how I would describe my Wilber's, I'm sure the Hagons are much the same.
The alternative is too much damping and not enough spring, creating a ride that can be smooth, supple, and confidence inspiring, yet wallows in turns, resulting in lower cornering limits.
The stock stuff combines a too low spring rate with a too low compression damping rate and virtually non-existent rebound damping, pretty much a triple threat.