Hi,
Over the years, I have made notes on the wiring of my Fulvia (S2 1600) and compared this with the factory wiring diagrams. It contains a list of all the electrical items on each fuse and is very close to the Lancia standard. There should be a copy of my notes in the downloads section (called 'Lancia Fulvia wiring notes S2') but I can send you an updated version if you PM me.
The wiring on my UK car placed the inner driving lights on fuse 7 (avvis), along with the horns and radio (with optional electric aerial), so this would have been the most likely candidate for a 25A fuse. However, unless all the wiring between this fuse and the battery is also rated for this current, its probably best to stick to 16A and risk a blown fuse, rather than a melted wire. Another interesting feature (not clear if this is unusual) is that the live side of fuse 9 (spie acciens, on the left side of the fusebox) is at the top of the fuse and the load is attached to the bottom. For all the others, the live side is at the bottom of the fuse and the loads are at the top. No idea why. I am using torpedo fuses with ceramic cores (from Frosts) in the hope that these will stop the plastic fusebox cover melting when fuses blow.
There are 2 additional, in-line, 8A fuses in my car. One protects the radiator fan and is positioned at the fan. The second is attached to the battery positive terminal in the engine bay and supplies the accessory charging bracket (used for a torch and other accessories) that is located under the dash on the RHS. I have now used this circuit to power a couple of USB ports for phone and sat nav, discreetly located in the glovebox.
Glyn