Hi all,
I noticed that there was a mistake in my previous code.

in includes/modules/yourtemplate/product_listing_php find
PHP Code:
$lc_text .= '<br />' . (zen_get_show_product_switch($listing->fields['products_id'], 'ALWAYS_FREE_SHIPPING_IMAGE_SWITCH') ? (zen_get_product_is_always_free_shipping($listing->fields['products_id']) ? TEXT_PRODUCT_FREE_SHIPPING_ICON '' '') : ''); 
and substitute with

PHP Code:
$clean_normal_price zen_get_products_base_price($listing->fields['products_id']);
$clean_special_price zen_get_products_special_price($listing->fields['products_id']);
if  (
$clean_normal_price >= $clean_special_price) {
    
$rcs_price $clean_special_price;
    }
if (
$clean_special_price == ''){
    
$rcs_price $clean_normal_price;
    }
      
$lc_text .= '' . (zen_get_show_product_switch($listing->fields['products_id'], 'ALWAYS_FREE_SHIPPING_IMAGE_SWITCH') ? (zen_get_product_is_always_free_shipping($listing->fields['products_id'])|| (($rcs_price * [COLOR="#FF0000"]1.22[/COLOR]) >= (MODULE_SHIPPING_FREEOPTIONS_TOTAL_MIN)) ? TEXT_PRODUCT_FREE_SHIPPING_ICON '' '') : ''); 
in includes/templates/yourtemplate/tpl_product_info_display.php find

PHP Code:
    <!--bof free ship icon  -->
<?php if(zen_get_product_is_always_free_shipping($products_id_current) && $flag_show_product_info_free_shipping) { ?>
<div id="freeShippingIcon"><?php echo TEXT_PRODUCT_FREE_SHIPPING_ICON?></div>
<?php ?>
<!--eof free ship icon  -->
and substitute with

PHP Code:
<!--bof free ship icon  -->
<?php    
$clean_normal_price 
zen_get_products_base_price((int)$_GET['products_id']);
$clean_special_price zen_get_products_special_price((int)$_GET['products_id']);

if  (
$clean_normal_price >= $clean_special_price) {
    
$rcs_price $clean_special_price;
    }
if (
$clean_special_price == ''){
    
$rcs_price $clean_normal_price;
    }
?>

<?php if((zen_get_product_is_always_free_shipping($products_id_current) && $flag_show_product_info_free_shipping)|| $rcs_price * [COLOR="#FF0000"]1.22 [/COLOR]>=MODULE_SHIPPING_FREEOPTIONS_TOTAL_MIN){ ?>
<div id="freeShippingIcon"><?php echo TEXT_PRODUCT_FREE_SHIPPING_ICON?></div>
<?php ?>
<!--eof free ship icon  -->
There is an hard coding that I did and it is the VAT adding (1.22 in red)
It is needed to change this to your vat value or better if some knows how to get the value from the db (i spent hours but I did not make it out) please let me know so the code will be more automated for everyone.

Ciao from Italy
enzo