Seriously tho, Hagons are a top quality shock with the benifit of adjustable rebound damping for a smoother more controlled ride. Not sure what the stock length of the shocks are on the roadster, only that they're 12.5" on the R3/classic Ring Hagon for the length you require( they do them in 10mm steps on size) & the weight of spring ( according to your body weight) Alternatives are the Progressive range of springs, also good, but my preference is for Hagon Nitro.
If you put say a half inch shorter on the back, drop the forks by a half inch ( dealer can do that) to maintain the balance of trail.
Word of caution, lowering the shocks reduces ground clearance... this may or may not be an issue depending on how hard you ride.