Their first order of business is to decide on a proper car stereo head unit. This is the main control unit for the entire system and comes in the form of a tuner, CD player or cassette player or a combination of the two. These days most people go with a CD player head unit as they are the most accessible and most people buy CDs in their musical selection instead of cassette tapes that are somewhat difficult to find in those days.
The main unit must be connected into the existing stereo unit rests. The two can be different sizes so you'll probably have to buy 
a universal mounting kit. They are available from most large retailers and run under $ 25. Also, you should get a universal wiring harness to make installation go more smoothly. If you have no knowledge of car wiring systems it is easy to short circuit the car or stereo, if you do not know what you are doing. Universal Wiring harnesses come with detailed instructions on assembling the wires Automotive type.
Next you need to determine speakers for your sound system. This can be a tough decision depending on what your basic needs. There are several speaker systems to choose from, and you must pay close attention to the main unit, you have bought, because it will tell you how many speakers it can handle on their own. Be sure to check the power rating and size of the speakers. You have so much space to work with in your car without taking away from passenger space. But some prefer to use the trunk space to mount speakers and other accessories.
Along with speakers is the amplifier. The amplifier is a device that will increase the overall power and provide better quality high volume sound to your system. Amplifiers are available in many different sizes and prices, depending on the power you want to get to your car audio system.
Extras would include MP3 hook up adapters, bass boosters, compact disc changers, and lights. All these are available from major retailers nationwide. You can spend a little or much, depending on brand and quality you want.
Remember that the more complicated a car sound system the harder it is to install. Some companies that sell complete systems offer free installation with a purchase. This is a wise choice for people who know little about car stereo installation. Not only will the equipment be installed properly to guard against malfunction but it will also look good. Part of installing a system is running wires and capping lines that can be difficult for anyone in doubt about what they are doing.
