Ok well the cheapest way to intergrate a system without a aftermarket h/u is a line output converter, simple to install you can put it behind the factory radio or if you can access any off the speaker wires tap in there. You need a 2channel for just a sub amp,it just taps into the audio out from the radio, they usually have 4 wires two positive and two negative, so buy one and look up the vehicles wiring diagram if you don't already know which wires are pos and neg for each speaker, just tap into one speaker. If you have a bestbuy close to you then go there website and do a search for line output converter. Then go to the store with the sku number or item information. They are usually like 15 to 30 dollars. Or go to a car audio shop. And ask for a line out converter. Good luck you will need an amp kit and rcas. Also if your factory stereo system has a factory upgraded system such as bose or jbl or infinity it does make a difference when installing a loc. Let us know if ya need anything else