Car audio enthusiasts love competing with one another to see who's vehicle can produce the most sound. Often times they'll populate vacant parking lots, or side-streets and blast their sound systems as loud as they can go. Sound pressure level (SPL) wars can have glass-shattering effects on a vehicle. Some competitions may have technical equipment to determine which audio system reaches the highest decibel, others just rely on popular opinion. Either way, it's a fun way of discovering different ways to modify your car audio.
An organization that has been in the car audio competition for awhile is the International Auto Sound Challenge Association (IASCA). They have a Bass Boxing competition with five divisions that mimic the divisions you see in boxing (flyweight, heavyweight, etc). It's one of their most popular categories as it often draws in large crowds and has unique and exciting modified vehicles soley dedicated to low bass sounds. Other organizations include the USACI and dB Drag Racing.
If you want to install your own car stereo system, there are important things you should know before getting started. For instance, a good car stereo system will have a head unit (the in-dash CD player in your car) two main speakers, an amplifier (increases signals to enable better sound), and a subwoofer (improves bass sound). It can be complicated as you have to deal with wiring, but you could also get a professional installation, costing a little bit extra. It's obvious, though, that people are paying more attention to their car audio, since the NDP Group saw increased sales in A/V multimedia head units and in-dash navigation units earlier this year. And with technology advancing the way it is, you'll definitely find a car audio entertainment system with the features you want.
SPL wars are fun to watch. If you've never been to one there are tons of YouTube videos of tricked out car audio demonstrations in action. You'll even find videos of people driving through fast food restaurants with systems turned all the way up, though I'd advise against that since disturbing the peace is a misdemeanor; it's best to just keep it in an approved area where everyone knows that loud music is going to be played.
Audio is only part of the wide range of entertainment possibilities while on the road. You can add navigational devices in your vehicle (not as entertaining, but it's no fun getting lost!). You can watch movies or television via a car overhead DVD player, or you can play video games from your favorite game console; all you need is an A/V cable. There's always something to do in a car decked out with the best in-car entertainment technology.