Simple Mod to Enhance Ultegra 8070 Di2 Rear Derailleur weight.

Here is a Simple cost effective Mod to Enhance Ultegra 8070 Di2 Rear Derailleur weight.
Simply swap the Ultegra 8070 Aluminium cage to a Dura Ace 9170 Carbon cage.
With this simple mod a weight savings of nearly 20g (19g) can be achieved.