Setting your system goals - Getting started.
As I have said before, the most important aspect of designing a reliable, great sounding system is to have a plan. Before starting work on any large system, or before someone starts selling equipment to a customer, there are several questions that need to be answered.
These questions will help determine the equipment that will be required for the car, and the complexity of that installation.
The make and model of the car will help to determine the location of the speakers. A car like an Impala has lots of room for large kick panels. A smaller car, with a small center console, such as a Mazda Protege, or Chevy Cavalier may prove to be a good candidate for a set of Horn Loaded compression drivers (HLCDs). Cars with larger center consoles can prove to be challenging, and high tweeter placements may result in the best soundstage.
If the owner listens to dance, rap or other synthesized music, then emphasis on subwoofer choice and enclosure design will be much different than that of a listener who enjoys jazz or classical. People who listen to naturally produced music are most likely to be able to criticize a system, because they know what the music should sound like. The flip side is, there are lots of people who come of the 'more is better' camp, and today's efficient amplifiers and subwoofers can easily meet their needs.
How loud people want their music is going to determine how much power they will need, and usually how many woofers will be required for the system. If someone should ask that the system be extremely loud, but they listen to jazz, this is a warning that they may not be sure what they want. Your best bet is to listen to some other cars, and decide what is enough for you.
That being said, I believe that you can never truly have too much power in a system. I have worked on sound quality systems running more than 1200 Watts into a single four-inch center channel speaker, simply to ensure adequate dynamic range.
If you are planning a competition system, then you will need to become intimately familiar with ALL the rules from the sanctioning body you have chosen. IASCA and USACi rule books explain what you get points for, and where you loose them. Common sense is the only way to figure out who to obtain a perfect score. For dB Drag Racing and IdBL, your creativity and imagination, combine with the rules and the laws of physics will determine how loud things get.
If the car is to be shown in an audio competition, at a car show, or in a magazine, you will need to ensure that even the most minor of details is taken care of. The grain and texture of vinyl must match anything existing, and run in the same direction. Seams must be done in a similar fashion as the rest of the car. Color must be matched perfectly. Also, the 'lines' of anything you add must flow with the factory lines. Holes must be perfect, screw heads aligned, and so on. Showing work that was not done correctly is never worth the hassle.
The last and most important factor is always budget. You can't buy a Lincoln Mark 8 LSC for $199.99 a month, so don't expect your audio system to perform like an IASCA or dB Drag car if you haven't spent the time and money. You need to be reasonable with your goals. If overall sound quality is your goal, then focus on speakers and their placement. If SPL is your fix, then amplifiers, batteries and cone area are your areas of focus. If you are on a budget, Lighting should be foregone in replacement for an upgrade in equipment quality.
Once you have a plan, carve it in stone. Do not stray from it, under any circumstance. if you plan changes, stop the project, and rethink your overall objective. If you are willing to substitute location or equipment, then perhaps your plan wasn't right in the first place. Research before you start building and buying will pay off.