Hi,
Open this PHP file:
/templates/YOUR_TEMPLATE/html/com_virtuemart/productdetails/default.php
(default.php or flexv2.php which ever you are using for the product details page layout)
and look for this line:
<a title="<?php echo $ManufacturerName; ?>" rev="iframe|550|650" rel="facebox" href="<?php echo $ManufacturerLink ?>"><img src="<?php echo $this->product->mf_images[0]->file_url_thumb; ?>" alt="<?php echo $ManufacturerName; ?>" /></a>
and
replace it with this:
<a title="<?php echo $ManufacturerName; ?>" href="<?php echo JRoute::_('index.php?option=com_virtuemart&view=category&virtuemart_manufacturer_id=' . $this->product->virtuemart_manufacturer_id); ?>"><img src="<?php echo $this->product->mf_images[0]->file_url_thumb; ?>" alt="<?php echo $ManufacturerName; ?>" /></a>
Then you will get what you need.
The next page will show all the products from that specific manufacturer. There will be no popup.
Regards.