Everybody needs a nice home, and that includes your subs. Look, they're going to spend all day in the trunk, shouldn't you make them as comfy as possible? Be considerate and buy some subwoofer enclosure accessories.
SoundDomain: Subwoofer Solutions
Elite Car Audio: High End Car Audio Talk
the12Volt: Car Audio Talk
Polk Audio: Car Audio Talk
Audio Forum: Subs and Enclosures
Crutchfield: Subwoofer Installation Guide
Crutchfield: Matching Subs & Amps
Crutchfield: Subwoofer Wiring Diagrams
Polk Audio: Subwoofer Wiring and Bass Management
eCoustics: Consumer Reviews
DIY Network: Installing a Subwoofer
Term Pro: Building a High-End Subwoofer Enclosure
Custom Car Stereo: Box Calculator
Wikipedia: Subwoofers
Crutchfield: Subwoofer sd_redesignping Page
Polk Audio: Car Audio Product Page
Power Acoustik: Car Audio Product Page
SAS Bazooka: Car Audio Product Page
Boss Audio: Car Audio Product Page
Clarion: Car Audio Product Page
Eclipse: Car Audio Product Page
Image Dynamics: Car Audio Product Page
Infinity: Car Audio Product Page
JBL: Car Audio Product Page
Kicker: Car Audio Product Page
MTX: Car Audio Product Page
JL Audio: Car Audio Product Page
Memphis Car Audio: Car Audio Product Page
Precision Power: Car Audio Product Page
Orion Car Audio: Car Audio Product Page
Pioneer: Car Audio Product Page
Rockford Fosgate: Car Audio Product Page
Lanzar: Car Audio Product Page
Hifonics: Car Audio Product Page
MB Quart: Car Audio Product Page
Alpine: Car Audio Product Page
Kenwood: Car Audio Product Page
Panasonic: Car Audio Product Page
Alpha Sonik: Car Audio Product Page
Focal: Car Audio Product Page
Boston Acoustics: Car Audio Product Page
CDT Audio: Car Audio Product Page
Cerwin Vega: Car Audio Product Page
Diamond Audio: Car Audio Product Page
Lightningh Audio: Car Audio Product Page
MMATS: Car Audio Product Page
Morel: Car Audio Product Page
RE Audio: Car Audio Product Page
Visonik: Car Audio Product Page