[quote=green-ghost]I had louvers on the back and sides of my mustang and the visibility was a little diminished but not terrible. /quote]

Same here. I had them on my '78 Z28 and had very little difference in visibility. They were metal and I kept them securely clamped down to avoid any rattles.

The only problem I had with them was keeping the black paint looking new. The hot Texas sun was brutal on it. UV resistant plastic would be much better.