So I kinda answered my own question...
Parts Diagram for Audi A4:
https://nemigaparts.com/cat_spares/etka/audi/a4/223u/409150/
Indicates
M10x48 bolts for DS x Flange joints.
Parts Diagram for Porsche Boxster:
https://nemigaparts.com/cat_spares/pet/porsche/986/520u/501050/
Indicates
M8x50 bolts for DS x Flange joints.
So who has a set they'd like to sell?