I did it but the featured products still not filtered.
EDIT: i.e., the featured header remains with same products (3 in my case). I think they could disappear or be filtered same as all others products in category. So the customer will have focus only on the desired products. If the customer wants to filter the category, he doesn't want to see the featured products header anymore. Am I right?
Any other help? It could be set invisible/visible by jquery, it is an option.
Featured products are always visible in nopCommerce because that is their idea to be "featured".
If you don't want featured products then simply don't mark any products as featured products (for the given category) and they won't be shown.
The normal products panel (the panel with the pager, view mode, view per page options) is the one that can be changed by the Ajax Filters. The setting from the Iliyan's post will just make nopCommerce to include the featured products in the normal list of products (otherwise they are ignored and become not filterable) and let you filter them inside the filterable panel. But the panel with with the featured products will stay untouched.