I try to answer.
The stickers are produced from a friend Emanuel & co, you'll find on ebay under africa twin stickers. These were specific for this bike.
My tanks are in aluminium, really lighter than the original. The rear tank is also the frame, there is not the original under seat frame, just the tank. I didn't get the weight of the bike jet but it is really lighter than the stock one. At least 20 kg less.