1. Amplifier Installation Kit: contains all parts necessary to install a amplifier.

2. Power, Ground, & Remote Cable: The power cable (red)is ran from the battery to the amplifier. To run the power cable you will either have to find an unused grommet(black rubber plug) in the fire wall or you will have to drill a new hole. In most cars you should have no trouble finding one. When you find one, pull it out and punch a hole through it large enough to fit the power wire through. You could also use a small amount of silicon to seal the hole. This way you will have a water tight fit when you put the wire in. The ground cable(black) is ran from the amp to a ground point on the car. The ground wire shouldn't be any longer than 24 inches. If possible try to use a pre-existing bolt to ground the wire. Whether you find a suitable bolt to use or if you have to drill a new hole, make sure you remove any paint to ensure good grounding. Depending on how much current the amp draws, you will need a certain gauge wire. Ask your retailer for details. The remote wire(usually blue) is ran from the remote wire on the head unit to the remote wire connection on the amp. This wire is responsible for turning the amp on and off when ever the head unit is on/off.

3. RCA Cables: This cable is used to carry the audio signal from head unit/equalizer/or electronic crossover to the amplifier. The RCA cable should be ran separately from the power wire to avoid possible noise issues. If you are installing the amp in your trunk you will most likely need a 20 ft. cable. If you are installing an amp where the head unit does not have RCA preouts (only stock units have this problem,) you will have to buy a converter box that converts speaker wire into RCA signal. This produces a signal poorer in quality but it works. What you need to do is splice the box into the rear speaker wire and then run the RCA cables to the amp.

4. Battery Terminal Connector: These will usually have to be bought separate from the install kit and will cost around $15 & up. Most of these are gold plated to decrease resistance.

5. Battery Terminal adapters: These are required for side mount batteries commonly found in compact cars.

6. Inline Fuse Holder: This is placed inline with the power cable no further than a 1 foot from the battery. The further it is from the battery the more chance there is for an electrical fire to happen. One of these is included with most kits. The purpose of this fuse holder is not to protect the amp, it's purpose is to protect the wire incase of a short between the battery and the amp.

7. Solderless Connectors: These are used to connect power and ground cables to the battery, amp, and grounding point. They are connected to the wire by either crimping them or by a set screw.

8. Split Wire Loom: This is a corrugated tubing with a split down its center through which wires are placed. It protects wire that is ran under the carpet, in the trunk, and under the hood, from damage. You have most likely seen this ran throughout your car. Most amp kits I've seen either don't come with it or they don't come with enough. A lot of the kits I've seen only come with enough loom to protect the wire that is run under the hood(about 5ft.) Wire loom should be used along the entire run of the power cable, RCA cable, speaker cable and so on and so on. I know I've spent over $100 in cables and I don't want to have to replace any of them. This whole section was taken from http://www.redrival.com/ixlnxtc24/ampkit.htm . I have added and edited some parts. Although this is very good, there are some other things that he left out. When you get your amp kit, you will have to strip all the wires, install all connector pieces and inline fuse yourself. Also, remember to run the wires before doing this. I learned that the hard way. Here are some pictures of my install.

This is a close up of the inline fuse. Notice how it is secured to wires running parallel to it. Don't be stingy with the wire ties.

This is where the wire goes through the firewall. I used one of the stock holes for this, but if you look to the left of that hole you can see one I have drilled for other aftermarket wiring schemes.

Although some amps may differ in layout...this is the way one of mine looks. 1. This is the ground cable hook-up.
2. Power cable hook-up.
3. These are the speaker wire outputs. This particular unit is bridged for a subwoofer.
4. This is the remote wire hook-up. (Most of the time the power, ground, and remote plugs are all next to each other. The amp's manual will lay them out.)
5. These are the RCA inputs.

This is a splitter box. It is necessary when hooking up multiple amps. It turns the 4 gauge wire coming in from the battery to four (only two hooked up) separate eight gauge wires.

These are my ground wires. They are bolted down in the spare tire wheel well. Notice how all of the surrounding paint has been sanded off to ensure a good connection.