Ghost's suggestion showed me the name of the manufacturer in the link, but didn't redirect to the concerning manufacturers page. That got me thinking if the path was correct. The manufacturers are only set as manufacturers, not as categories or menu-items.
So instead, I've been trying to find the right link:
1.
In the CustomFiltersPro-module (back-end). The only thing I could find that made sense was in this menu-item:
index.php?option=com_customfilters&view=products
So comparing this with what I had, I came to this:
$link = JRoute::_('index.php?option=com_customfilters&view=category&virtuemart_manufacturer_id=' . $this->product->virtuemart_manufacturer_id[0]);
This leads to the right page, with all the products of the manufacturer (the page is just not styled correctly, but that's a minor thing).
Only thing is: is this a correct url? Can it be cleaned up so it's a nicer url, and can it show the manufacturers name instead of the id?
For instance, when clicking 'Triumph', the link is:
http://websiteurl.com/index.php/component/customfilters/?view=category&virtuemart_manufacturer_id=1
2.
Directly through the customfilters-module in the front-end.
The link to the same manufacturer 'Triumph' for instance is:
http://websiteurl.com/index.php/zoeken-in-webshop/no-category/triumph
What would be the best way and how to retrieve the most clean, right url?