Stefan,
Sorry for being late on this one…
Found it… not sure why I never caught this before, but the code actually does reside in the File Upload module code 
In mod.file_upload.php (in modules/file_upload folder), around line 387:
Change:
if ($data['is_image'] == 1)
{
$imgsrc = "<img src=\"{filedir_".$data['id']."}".$data['file_name']."\"".$properties;
$wh = '';
if (function_exists('getimagesize'))
{
$imgdim = @getimagesize($query->row['server_path'].$data['file_name']);
if (is_array($imgdim))
{
$imgsrc .= " width=\"".$imgdim['0']."\" height=\"".$imgdim['1']."\"";
$wh = "width=".($imgdim['0']+15).",height=".($imgdim['1']+15).",";
}
}
$imgsrc .= " />";
To:
if ($data['is_image'] == 2)
{
$imgsrc = "{filedir_".$data['id']."}".$data['file_name']."".$properties;
$wh = '';
if (function_exists('getimagesize'))
{
$imgdim = @getimagesize($query->row['server_path'].$data['file_name']);
if (is_array($imgdim))
{
$imgsrc .= "";
$wh = "width=".($imgdim['0']+15).",height=".($imgdim['1']+15).",";
}
}
$imgsrc .= "";
And around line 413:
Change:
else
{
$props .= "<a href=\"{filedir_".$data['id']."}".$data['file_name']."\">".$data['file_name']."</a>";
}
To:
else
{
$props .= "{filedir_".$data['id']."}".$data['file_name']."";
}
