They mean that you still have the stock dpf particulate filter on the truck which causes the poor fuel economy. The kits are pretty pricy
but in the end the better economy and how much you will save at the pump, it pays for itself. Here is a link to give you an estimate on the price.http://puredpfdelete.com/catalog/dodge/index.php
Also you may want to consider a cold air intake too. Is it an auto or stick?