Had my back plastic replaced about a year ago at a dedicated convertible top shop, they charged me 450.00. I was very disappointed with the results. So I'm sharing my story to maybe give you some other insight. I was under the impression that they were going to remove the old plastic and replace with a new one. What they
did do was, sew in a new "clear" plastic under the old plastic and then cut out the old window. What was left was a frame of a very jagged edge of the old plastic layered over the new plastic. It stuck out of as much as 1/2 an inch in some places,
they said they had to do it that way to prevent wrinkles in the new plastic. Also it
was not watertight. The first gentle rain we had, the water soaked right into my
carpet above the engine. After complaining to the owner, he said that If I came back in, he would look at it and possibly refund half the money. I didn't even bother to go back in. So what I did was get out my old trusty xacto knife and trim the old plastic edge all the way down to the canvas, then I sealed it with some black RTV, It looks 100 times better and now there are no leaks. I will try to post some pics when i get a chance. Also found out later that they even used the wrong plastic. There is a green tinted plastic that should be used on all Porsches. I am going to replace it with a glass window top when the canvas wears out, although I heard that the dealer might charge extra to do any maintenance where the glass top will get in the way because they cant fold it. Good luck!!

German canvas is cotton American is polyester!!!!!