I mounted mine on the plastic A/C duct under the dash. I did put two small screw holes in it but it's just the plastic duct and easily replaceable if need be.
Also I taped a piece of sandpaper, grit out, to the area in which I wanted to mount the pod. By doing this, I was able to carefully rub the pod back and forth across the sandpaper until it conformed to the shape of the duct.
Not a great pic since it was before I mounted it back into the car but you get the idea. Also, I painted the pod the color of the dash. I need to redo the 'chrome'... It's just silver paint.
