I installed these soon after I picked up my 919 last August. Only thing I can think of, for obvious reasons don't take all of the engine bolts out at the same time. When reassembling one of the bolts did not quite line up after, so I had to jack under the engine maybe 1/8" higher to get it to go in. I was able to install them by my self, but a second set of hands would always help. I did notice a new vibration just under 3000 rpm after installing that is still there 8 months later. Not bad just barely noticeable if you stay at that rpm while not accelerating.