replacing all the bolts and nuts by such from alluminium was saving another 500g.
But!!! only these bolts which re not used for mountings with high load. You should not replace the bolts from the brake calipers
Unfortunatelly i lost the list with all the sizes some years ago
Removing the electrical starter, the starter flywheel and the batterie saves 6,5kg (if i remember right)
My #uno was about 150kg + with full tank