Because of the potential power available in a good subwoofer response, one will have to use a special subwoofer speaker wire. Standard 18- or 20-gauge speaker wire will not be able to deliver the same type of range that you will find with Monster wire. Monster wire, which is typically braided wire, is able to carry a better bass response because there is more surface area along which a signal can travel. Any electrical signal does not travel down the center of a wire, relying instead, on the surface of the wire. Thus, the more surface area you can expose, the better it is for our response.
For more info, see What Are the Best Car Subwoofer Speakers?