Subwoofer considerations:

Car subwoofers are loudspeakers intended specifically to produce strong bass audio frequencies. By serving as a supplement for your door speakers that primarily cover higher frequencies, car subwoofers operate in the 10 Hz - 100 Hz range and will give you that added low end that you're looking for. With car subwoofers, your sound system can most accurately reproduce sounds such as tuba, bass guitar and other low frequency instruments. However, you do have a variety of choices to make about which specific types of subwoofers to use.

What to look for in car subwoofers:

To survive the rigors of being in a car, subwoofer cones must be made out of durable poly fibers and other synthetic materials to help ensure accurate response and to sustain the harsh environment of the automobile. The subwoofer structure known as the basket also needs to be made out of a strong material; usually these are stamped steel for lower cost models and cast aluminum for more high performance models. These structures ensure the subwoofer remains rigid under high volume and maintains the proper gap of the voice coil.

Subwoofer size:

Subwoofers come in a variety of sizes from 6 to 18 inches to fit your car or truck's needs. With size comes a differing need in power, A small subwoofer can use as little as 25 watts of power and provide a minimal bass. But for the mind numbing bass you will need a large amount of power and multiple or larger cone subwoofers. It’s best to match an amplifiers RMS output to the RMS input of a woofer so that you have adequate power for your system. With more power you get more heat and subwoofers must be able to dissipate that heat. Most subwoofers address this issue with different cooling technologies such as vented pole piece and vented magnet structures.

Single vs Dual Voice Coil

The single voice coil or dual voice coil, otherwise known as SVC or DVC respectively, affect your power usage and amplifier loading. Single voice coil car subwoofers have fewer wiring options when using more than one driver, dual voice coil subwoofers offer considerably more wiring options and are easier to properly load an amplifier if using multiple drivers. There is no audio performance differential between these two types of systems, so choosing an SVC subwoofer may be entirely sufficient for your purposes.

Low Profile vs Normal Profile

Low profile car subwoofers, otherwise known as shallow mount, can be used to provide a level of bass that most subwoofers cannot produce while using a smaller box size. Often, normal profile subwoofers will not fit into the space under a hatch or in a door, while low profile car subwoofers will add this flexibility to your audio design.

Ported vs Sealed Enclosure Design

Sealed subwoofers use a cushion of air within the subwoofer box to control the bass your car subwoofers produce, allowing the audio to be more flat in response with a precise and controlled roll-off. These systems will also fit into more types of cars than will ported subwoofers. However, sealed subwoofers take more power and produce tighter bass due to this moderation. With a port in the subwoofer box, air flow allows for better cooling, longer subwoofer life, and more raw volume to your bass. The difference is punchy sound versus thundering sound with a trade off of excessive excursion below the port tuning frequency, so a subsonic filter on your amplifier is a must

RMS Power vs Peak Power

The amount of power handling that car subwoofers can work with is a function of what the amplifier can send to the subwoofer without causing damage. RMS or root mean square is an average of the power that your car subwoofers can continually handle without being damaged -- as in over an entire album. By contrast, the peak power your subwoofers can handle is a function of how much they can work with during a short period, such as during the crescendo of a classical piece or a screaming rock finale.