I run 2 sets of bar end weights one inside the bark busters and the other on the outside with extra long bolts. I also use liquid bar snake ( but they do not make that product anymore ) in the bars to dampen the vibrations. My mirrors work great at any speed.
I do it to keep my nerves from tingling (carpel tunnel) or hands from getting numb.
2013 Ducati Hypermotard SP, 2011 Husaberg FE570S, 2011 BMW S1000RR, 2010 BMW F800GS
2007 Husqvarna TE610 , 2003 KTM 525 MXC