Car stereo systems enthusiasts usually bridge their amplifiers. This job lets you divide the number of channels your amp uses while at the same it doubles up the power sent to each of your speakers. This will send a powerful mono signal to your sub woofers creating a more distinct and superb sound. Unprepared car owners with too much self confidence who do bridging may end up doing a serious damage to their audio systems or even harm themselves because of incorrect bridging. A step-by-step guide in amplifier bridging is a big help but you also need to consider some important things. First, you should be certain that your amplifier can be bridged. You can see this in your manual. Remember that two channel amplifiers can only be bridged into one, and a four channel is bridged into two channels. Doing a four channel into a two can be dangerous as it put too much energy into your alternator/speaker. For your safety, before actually trying to do anything, consult a trusted car audio stores. You can also see some online recommendations which you can find on Pep Boys twitter profile page.