Car Audio has basically built it's reputation around extremely loud bass systems. Those of us inside the industry who are fans of sound quality still appreciate the engineering and trial and error that goes into an SPL vehicle, but we prefer to focus on the accuracy and balance side of the car audio bass equation.

Subwoofer Power Ratings
Enclosure comparison chart
Enclosure design choices

Enclosure placement basics

Enclosure placement experiment
What to listen for
Thermal Power Handling