My bike came stock with 10-speed 6770 Di2 components already on it.. The shifters are custom K-Edge Ki2 (link: K-Edge Ki2: Electronic Mountain Bike Shifting)

To upgrade to 6870 11-speed I needed the following:

• 6870 Rear Derailleur
• 6870 Front Derailleur
• 6800 11-speed cassette
• 6800 11-speed chain
• 11-speed Freehub for my Roval Rapide SL-35's

I was told by both Specialized and Shimano that my old 6770 Front Derailleur would work but they recommended I also upgrade it to 6870 for best performance, so I did just that..

My crankset is Specialized Pro Carbon and it's already 11-speed compatible..

I purchased the 6870 parts from Jensen USA. They have some nice prices right now and they even price matched the FD.

I spent this for the upgrade:

• 6870 RD $200
• 6870 FD $200 (they price matched performance bike)
• 6800 cassette $72
• 6800 chain $32
• Freehub $80 (ordered through LBS)