Do your lights dim when your bass hits? If so, your electrical system is being strained, and your subs are not playing as well as they could. Not to mention that you may be wearing out your charging system prematurely.
A popular choice to deal with this problem is to add a capacitor to your system's wiring. However, capacitors have some disadvantages. They are expensive and often times too small for today's higher wattage amplifiers.
An alternative is to use a deep cycle battery (the kind you might find in a boat). A good choice is an Optima blue top, because it already has auxiliary posts on it, and it can be mounted in any direction. Just wire it in like you would a traditional capacitor. Your alternator will keep it charged, and it will give your amp the additional power it needs to really hit those lows.
The main disadvantages to this setup is that it takes up more space, and if you mount the battery in the passenger compartment you run the risk of spilling acid in a bad accident. If you mount it in the car, use a battery box like drag racers do to keep yourself safe.
