70% of your sound of your subwoofer is due to the design and build quality of your sub enclosure. When picking a subwoofer box, deciding to either go sealed or ported will determine how your system will sound.

...read the full guide here with pics (http://rover.ebay.com/rover/1/711-1751-2978-71/1?AID=5463217&PID=2212781&mpre=http%3A%2F%2Freview s.ebay.com%2FPorted-vs-Sealed-Box-Enclosure_W0QQugidZ10000000001036431)

go vented if you like it boomy or you have a puny amplifier...go sealed if you like sound quality or you have the franken amp.