Have you listened to a Explode sub??. They leave a bit to be desired. You would be better off getting a small unloaded box..
Than getting a decent sub ( kicker comp VR, Alpine, Cerwin vega)
They don't cost THAT much more and if you are only using 1 Get some punch from it. A good way to look if you are using a low powered amp is sensitiveity the higer the better. It takes less to power. A good cheap sub is a JL10W0. BY JL cheap and pounds with a small amp....Good luck