Article: Check the owner's manual to find out what your speaker can handle. Understand how much power the current system can handle in terms of its electrical capability capacity.  First, how loud do you want your stereo to be? The amount of amp wattage doesn't necessarily translate to how loud your car audio will sound. However, having a lot of power available is good for "headroom", which is the ability to deliver a burst of sound when the music asks for one.   Be mindful if you drive a smaller car as a smaller amp will be adequate for its system. For example, an amp with 50 watts RMS per channel or smaller can overcome road noises and add clarity. Ensure you use speakers with a top RMS rating of at least 35 watts RMS with amps of this size.  For larger vehicles or for those who just want more volume, look to use an amp with a 75 watts RMS per channel setup. Amps of this size need speakers with a top RMS rating of 50 watts RMS or more.  If you want maximum volume, an amp with 100 watts RMS or more per channel will truly set you apart. Speakers or component sets rated with at least 75 watts RMS each can handle amps of this power. Amplifiers can be organized into a 4-class system based on efficiency, size and cost.  Class A is 25% efficient, which means that for every 100 watts of electricity used, only 25 of those watts go to power your speakers. These amps are considered low-quality and should not be used for cars. Class A/B amps are 50-60% efficient in their power use. They typically are smaller, use less power, and cost less than Class A designs. Most car audio amplifiers use this class of amps because of their efficiency and compact size. Class D is known as a switching amplifier that works well for subwoofer use. This class has better efficiency at a smaller size than Class A/B amps. This class of amps is 70-75% efficient in their power use. Class G/H designs use multiple output voltage levels for a 75-80% efficiency. At a low volume, these amplifiers remain at a low voltage. As you increase the volume, the amp utilizes the second (higher) voltage level, and at the highest volume all voltages combine to maximize your output. These amplifiers are smaller in size with relatively higher power output compared to Class A/B amps. Your amp should be at least three feet from the receiver to eliminate distortion produced from your vehicle's electrical system.  Don't bolt your amplifier directly to your car's metal chassis as noise problems, like ground loops that hum or buzz, are easily generated. Use rubber grommets around the mounting screws to isolate the case or mount your amp onto a wooden board and attach it to your car.  Keep your amp cool. An amp produces heat, which its heatsink absorbs and radiates, so keep a few inches of air space around it to allow the heat to dissipate. Keep the fins on the heatsink vertical if you're placing your amp on the wall of your car. Never mount an amp upside down, as this won't allow heat to dissipate but rather radiate back into the amp.  Make room on either side of your amp for wiring connections. You also need enough room to adjust controls like gain, crossover, bass boost, etc.  Common places to store your amp are under the seat or in the trunk, as wires can be easily hidden and controls are easily accessed. Use a 1/2" wrench to loosen the negative battery clamp and your fingers to remove it from the battery.  If it's stuck, use pry bars to pry open the soft lead battery cable end.  Make sure to disconnect the negative side first; if the wrench slips while you're disconnecting the positive side, it can form an arc that will shock you. Remove jewelry, especially rings. If you are accidentally shocked, the heat produced can melt jewelry into your skin.  Check your owner's manual, but generally, positive is red and negative is black. You should also look for (+) positive and (-) negative signs. Create a pilot hole with a power drill and steel bit, then use larger bits to expand the hole into the proper width to fit your wire after a rubber grommet is used. Make sure the hole does not have any sharp burr or it will short to the amp wires. Connect your amp's Power Supply Wire from the positive slot to the corresponding positive terminal on your battery.  To determine which is the positive terminal on your amp, look for red or the positive (+) sign. Use a rubber grommet so that the wire doesn't rub and chafe as this can cause a fire. Check the area before drilling as you want to avoid hitting the cables of other components.  Insert a fuse at the battery to protect your car from catching fire as well as another fuse at the amp to protect it in case of a short. Remove the nut from the battery terminal. Slip the power cable's ring over the bolt that secures the battery terminal to the battery post, and replace the nut.   Many cables in wiring kits come with ring terminals. In case you don't have one, crimp it onto the end of the power cable before proceeding. Make sure that the wire does not have an opportunity to get pinched, kinked or rubbed as you drive. Use a bolt in your car's metal frame that's as close to your amp as possible. Drill a hole and add a ground screw or bolt if you can't find one but check for your wiring, gas tank, or brake line before drilling. Crimp a ring terminal to the short piece of ground cable.  Scrape away any paint and clean the grounding location of your car's metal frame thoroughly before installing the bolt. Keep this connection tight, clean, and electrically conductive with a lock washer, a star washer, extra screws, or any other grounding technique. Washers are inexpensive and can be purchased at your local hardware store and are also known as O- rings. Don't use any bolts that are part of your seat belt because this can compromise its integrity and your safety. If these screws don't come with your amp's installation kit, buy them at your local hardware store and simply line up your amplifier, and drill in the screws making sure you have proper clearance for the screws and they do not go into any thing other than the metal body. Neatly trim each wire, placing them in the desired position, and connect them. Make gentle curves with these wires if necessary as sharp bends could pinch. Cut small slits into your vehicle's carpeting so that you can run these wires underneath for a neat and professional aesthetic. Use an uncoiled wire coat hanger to thread your wire underneath the carpet if you lack the proper tools. Run each wire for your door speakers through the grommet to protect them from harsh weather or from getting pinched in the door. Remove your factory speaker wires. Connect the new wires that are connected to your amp directly to each speaker terminal.  Use 14 or 16 gauge wire for speakers and 12 or 14 gauge for subwoofers.   It is important that you keep the polarity of your speaker wiring straight by ensuring positive terminals connect with each other and negative ones do the same. This ensures that all the speaker cones have the same type of signal and move in the same direction, creating a balanced sound when played together. Turn on your car, then turn on the radio. There's an indicator light on your amp that will tell you if your amp has been initiated.Turn the volume up to an audible level and verify that sound is coming from each speaker and/or subwoofer in your system. Make sure all amp settings are at a minimum level before turning on your stereo system.

What is a summary?
Know your vehicle's capability. Choose the class of amplifier. Choose where you want to place your amp within your car. Disconnect the negative side of your car's battery. Drill a hole into your car's firewall to run your amplifier's Power Supply Wire through. Engage the power cable to the positive terminal of your battery. Ground the amplifier for safety. Mount your amplifier to the car using self-tapping screws. Attach the power and signal cables to the amplifier. Connect your amp to the rest of your sound system. Connect your battery and power up.