Hi, short question: does someone happen to know what is behind the original speaker depth in the door of a 850’s? Would you like to install better loudspeakers, but they might be a little deeper than the available space. Now I would like to cut out the sheet metal with a Dremel to get a little deeper. How much air would be behind it up to the disc? Is this possible or should I rather leave it? The door insulation is also such a question. Would you like to use Alubutyl to make the virde Is the dismantling a big problem? Thanks already for the help. mfg Frank