Cheers JP.The XS starter specs current draw at 12V 37A no load to 8.3V 100A @ full load 3000rpm (that's from the book). The short cable run makes a difference in you favor. Still 8ga would be pushing accepted boundaries, but doable on a "well tuned motor". 6ga more forgiving of extra cranking. Attached chart mostly useless (lengths), but gives an idea
Revival also state (on a motorbike) 12awg is more than enough for battery connection; not 6awg states in manual.