There is a fibreglass pad attached to the back seat . The pad is hog ringed onto the lower part of back seat .The pad is located above the muffler . This is a factory item , so the factory knew there was an issue with heat transfer from the muffler area floor pan to the seat . This heat shield pad was covered in plastic , so a bit of a pull to get back seat out when the plastic melted and burnt onto the floor pan . The floor pan above the muffler is so hot you can not put your hand on the floor pan . Not keen on putting the back seat / back in ! The car is a 1981 Capri with a 6cyl engine .Single exhaust . What can be done about this ? maybe wrong muffler was installed ? How common is this ?