Only in Beetles have I seen that and thats because some of the support(in my Notch at least) has a metal cross beam right across the middle of that little kick panel, and I wasn't going cutting things in Nellie.. 😉 I think Beetles don't have this brace running diagonally.
If you ask me, the less cutting into things, the better, and that includes interiors.
I ended up putting my speakers in a picnic basket and leaving it on the back seat. You have the look of old skool, but tunes and mp3 player in the glove box, running all the wires and amp under the carpet and mainly backseat. Schweet...
Up to you of course.
THE LOWEST WITH THE MOSTEST BLING BLING WINS!!