How do I change the size of the map in details view.

The size of the map in a listing details view are defined in this template file:

/components/com_mtree/templates/banyan/sub_map.tpl.php in line 5 - 6:

    $width = '100%';
    $height = '300px';

Changing the value of the width and height will resize the map in listing details view.