if they are still intact, which mine aren't:
- long ones at the rear into the subframe x 3
- 3 into the front bumper
- 2 per side for the arch linings
- and the famous awful bolts which have sheared off or rotate for probably half the A2-driving population who do their own oil changes and therefore have taken it off more than twice.
I don't honestly remember too much, because mine's normally held on with wishes, blutack, a couple of non-standard screws, cable ties and hope.
8 screws is a good start; 3 at the front, three at the rear, two per side.
- Bret
EDIT says here a definitive part number list:
https://a2-freun.de/forum/showpost.php?p=1147683&postcount=8
Partscat seems to think there are 10 screws involved, that's not unreasonable. But then the silver ones are additional, and 6 of those.
Take a look under the car and see where the tray fits.
Note also that teh tray actually keeps the arch linings where they're supposed to be. If you're running without it, at high speeds the linings can flap.