You lined the Seat backs with automotive carpet? Can I ask why and for you to explain this one a bit to me, is it for sound proofing?
It was just to protect the original boot floor and seat backs from stuff that goes in and out of my car as I use it for work. I didn't go for a vw liner as I thought it would muffle the sub, but it's such a low volume unit it didnt matter in the end.
However, now I have put my own liner in I was able to get it so that the seat backs are covered even with the seats down. So that turned out better and it was only £20 for the roll from Amazon.