So you are thinking a total rewire - not remove an X system only to fit another X system. Good plan and gives you real freedom. This is actually easier than trying to get hold of another X system [as you are in Australia like moi] and the outcome will be lighter, safer, more efficient and easier to fault find. I figure you already know that you can get Australian X wiring diagrams at
https://x19.com.au/manuals.html
If I were you and I do have some similar plans
- I would put the new fuse/relay box in the frunk next to the battery. My logic is that all the high power devices [except starter and carb fan] are in front of the windscreen [Australian car so no power windows or AC]. Radiator fan, headlights, horns, wipers. The stock design takes power for those from the battery all the way inside the car to under the dash at the stock fuse/relay set and then back out to the devices. Lots of extra wire, lots of voltage loss and lots of physical packaging difficulty. I would put the fuses/relays for the starter solenoid and carb fan in a separate marine style waterproof box in the engine bay. From a circuit logic POV, I would essentially copy the X design but with added relays for headlights and wipers. I also regard the frunk as a better place for the fuse box as it is more waterproof than under the dash in an open car and also much easier to do fault finding standing up.... And this moves some weight forward
The existing X system uses simple spade based connectors so I would replace the connector bodies while retaining the spades on the various sub-systems [like ignition switch]. Easy as.
