The field of car audio is currently set to reach close to $7 billion in the approaching years. This means that people aren't just satisfied with stock car audio kits anymore. You can upgrade your vehicle's audio with some of the best car audio accessories on the market. Here's what you should know. First, find out what kind of car stereo you have Consider the stereo that you already have in your vehicle and whether or not there are some accessories that improve its performance.