I know with my 1500 classic I was reaching and leaning a little forward and it was getting to me. On the VROC forum most of the 1500 riders were having to install risers to bring the bars back towards the rider and take some of the strain out of the lean and reach. I did that to mine and it seems to have fixed my back and neck. So the obvious thing would be to move them back toward you some and see how it feels. Now that I think about it, I moved my 750 bars back some after I got it too. I had the protac backrest on it too and have a good backrest on my 1500. I know that makes a huge difference, as does the floorboards.
Maybe your harley buddies are getting the kinks vibrated out while they ride?