This is how i fitted SWD class 108 sound. Sorry about the shakey camera work (no change there then !!) You can see how i cut down some of the glazing so it looks as though some of the windows are open. This improves the volume slightly. I have cut out a section of the interior lighting so the chip can sit ontop of the chassis block in the roof and still have working lights. Finally i cut out a section of seating for the speaker to fit and not be as obvious ! I tried both the 23mm speaker supplied and the 20x40 in a lower profile speaker housing, all supplied by SWD. The 20x40 speaker is a much better sound production in my honest opinion. See me other video of it running. Cheers