Installing a DIY Car Amplifier
Be sure that you know what's behind the spot where you are about to drill to avoid damaging any components. And for the perfect music output and avoidance of any mechanical issues, let your speaker polarity stay straight; thus, allow the positive wire from the speaker end up on the positive of the amp, and vice-versa. If you replaced the factory-installed speakers, the installation manual should tell you the impedance. Start from the interior of the car, and make sure the wire won't get pinched or caught on anything. I haven't played around that much with car speaker systems but I would recommend talking to somebody at a store that installs such systems to see how everything would be connected.