Hi Walter,
I put 5 1/2" speakers in my kick panels (blaupunkt of course!) On the right side I found a nice large hole in the metal behind the panel that I learned later was for access to the antenna. No such luck on the left side, so I got a large hole saw and cut one in the same position as the other one. Probably not the best way to do it as the blade wants to catch and rip the drill out of your hands. The trick is to go very slow and keep a firm grip on it.
Pete S.