Need 10 or 12 gage for the main runs. Its the male terminals and the doubles (two wires crimped into one terminal) that you want to make sure the crimpers can do well.
and wiring is like rocket science in chinese with a german translating it
How ya figure?
If it looks like a maze on paper, then take your electronic crayon and color it so you can follow it.
If it looks like a rats nest in the car, then label each connections with masking tape or whetever. Then take the whole thing out or at least far enough you can see everything. Clean it, photograph it and unwrap the tape. Copy as needed.