in the past, I have used
5mm spacers on 8th gen
8mm spacers on 8th gen
10 mm spacers on 8th gen
5 mm spacers on 9th gen
so i was confident that they will improve the stability as well.
but the main reason was the rear looks.
after changing to Si rear bumper, the wheel track looked narrow to me.
and this was also indicated by couple of friends