A RoadWing is a Honda Goldwing GL1800 mono shock (2001-2016) that has been modified and converted to fit on a Yamaha Road Star (any year). It is the brainchild of Chris Jones (aka Gonzodad on the Road Star Clinic). Chris has provided instructions on how to convert and install a RoadWing and has created a harness to utilize the Honda pump that increases/decreases the preload on the shock. You can check it out and buy one here
The dry weight of the Yamaha Road Star is between 677 – 743 lbs. The stock rear mono-shock is rated at 742 lbs. The dry weight of the Honda Gold Wing GL1800 is between 915-937 lbs. The stock mono shock is rated at 920 lbs. So just adding the RoadWing to your Road Star boosts your weight capacity 178 lbs. When you add the preload you boost it to over 1000 lbs. This is advantageous when riding two-up and aids in the handling of the bike, especially in the corners. No more bottoming out.
Most of the Yamaha Road Star owners who have a RoadWing installed on their bike say it is hands down the best upgrade for the Road Star. I installed a brand new take-off from a 2016 Goldwing on my 2094 Road Star and am thoroughly pleased with it.