[DIYguy]

They do not appear to have any purpose other than to hold on the sound tube diaphragm (see below).
Also, in the service manual this image came from there is no mention of having to drain anything when removing them.
So my guess is that they can be removed and left off the car.

I do not have a V8 in my car and there is no mention of the bit size in the manual.
Perhaps someone else who has a V8 can tell you.

Aha, JCunningham's reply came in just as mine did...... Thanks.