My board measures 6 X 12. It was not glued down and neither was the trunk mat. The underlayment is only on the axle tunnel. Since I had moved the board years ago I did not think to pay close attention to its exact location, my thought is that since it was not glued in place it could have been moved from its factory location long time ago before I acquired the car. However, looking at my board it looks to me as if the rough side was facing down and the smooth side towards the trunk mat. I surmise only because on the back rough side is a straight line rub mark which lines up with the far right rib on the top of the gas tank. I took a picture of the board with the rough side facing up and laying on top of the tank - the mark lines up the tank rib. I also conclude that since the rub mark extends the full length of the board, that the board was laid completely on top of the tank and not towards the end of the tank such that it would have been cantilevered past the tank's end. I took a number of pictures of the trunk from various angles and will post a few, I can post more if anyone desires to see them though they may wander off topic slightly. The 1st pic is the board's top surface, the 2nd is the bottom surface and the 3rd is the bottom surface up laid in place to show the rub mark aligning with the tank's top rib. I included the 4th picture to show the extent of the underlayment and where it ends.