We’re doing a bit of tuning on a 9000 groupo for a build. Shimano has really gone through their derailleurs and worked on the weight. Most all the bolts are aluminum and there’s no weight to really be lost anywhere without getting crazy. With that in mind we did loose 3-5 grams using the red HSC carbon pulleys which also upgraded the stock bearings to HSC’s high quality ceramic bearings. The rest, all the Far and Near Derailleur Tuning bits, are just for aesthetics and are really going to set the bike off.