1 and 2) The "upgrade" control arm bushings is the liquid-filled Boge 750i bushings. As Bruno and others have reported you can get a great deal by buying the Lemforder arms with the Boge 750i bushings already installed from BMA.Originally Posted by Crewblunts
3) Dinan's control bushings are basically the liquid-filled 750i bushing. Its my understanding that Steve Dinan was one of the first to discover this "upgrade" for the E28 5 series and is the only one of 2 sources I know of who sell a modify 750i bushing for the E28 (E28 control arms must be milled to fit the 750i bushing).
4 and 5) You should have all the rubber bushings in your front end examined and replace the ones that need it. For example, besides the upper control arm, take look at the lower arms, sway bar links, guibo/flex disc and all the rubber bushings in the rear. Oh yeah, don't forget the struts and shocks. Good Luck!