So this morning I was looking for a solution... and I managed to do it using javascript.
Maybe this can be raplaced with the actual limit image width function in the next xs release, I don't know how to replace, so for now I've just disabled the limit image width function and applied mine.
Here's what to do if you trust me

Disable the limit image width function (ACP - General configuration - Image width, and set at least the first 2 options to NO)
OPEN
/templates/ca_aphrodite/overall_header.tpl
FIND
<script language="JavaScript" type="text/javascript" src="language/{L_BBCB_MG_LANG}/bbcb_mg.js"></script>
Before, ADD
<script type="text/javascript">
function redimImg(foto, maxSize){
w = foto.width;
if (w > maxSize){
foto.width = maxSize;
}
}
</script>
function redimImg(foto, maxSize){
w = foto.width;
if (w > maxSize){
foto.width = maxSize;
}
}
</script>
OPEN
/templates/ca_aphrodite/bbcode.tpl
FIND
<!-- BEGIN img --><a href="{URL}"><img src="{URL}" border="0" alt="" /></a><!-- END img -->
REPLACE WITH
<!-- BEGIN img --><a href="{URL}"><img src="{URL}" border="0" alt="" onload="redimImg(this, YOUR_MAX_IMAGE_WIDTH_VALUE);" /></a><!-- END img -->
FIND
<!-- BEGIN albumimg --><a href="album_showpage.php?pic_id={IMG_NUM}" target="_blank" class="postlink"><img src="album_thumbnail.php?pic_id={IMG_NUM}" alt="Image" title="Image" border="0" /></a><!-- END albumimg -->
REPLACE WITH
<!-- BEGIN albumimg --><a href="album_showpage.php?pic_id={IMG_NUM}" target="_blank" class="postlink"><img src="album_thumbnail.php?pic_id={IMG_NUM}" alt="Image" title="Image" border="0" onload="redimImg(this, YOUR_MAX_IMAGE_WIDTH_VALUE);" /></a><!-- END albumimg -->
OPEN
/includes/bbcode.php
FIND
REPLACE WITH:
$html = '<img onload="redimImg(this, YOUR_MAX_IMAGE_WIDTH_VALUE);"';
OPEN
/album_mod/bbcode.php
FIND
REPLACE WITH:
$html = '<img onload="redimImg(this, YOUR_MAX_IMAGE_WIDTH_VALUE);"';