Another thing to consider when selecting a subwoofer is that it also needs power. This means you will either need to get a powered subwoofer, which has its own built-in amplifier, or you will need to buy a separate amplifier to power your sub. Sometimes people mount the amp right on the side of the sub box, but it all depends on size, space, location, and whether or not you want your stuff to be seen. Depending on where you live, you might not want to have a bunch of high-dollar stereo equipment just laying around in the back of your car to serve as an invitation for thieves.
Adding a subwoofer to your car’s audio system makes a big improvement to the sound, but knowing a little about your needs and limitations before you make a purchase will save you a lot of headache when you get ready for installation. Crank it up!