[Slow Play Ray]

Depends on the car, but I would say unless you are normally mechanically inclined (read: can/have installed your own car stereo and replaced something like your thermostat on your own), have a professional do it. And even if you are mechanically inclined, it still may not be worth the hassle. Some cars are a bitch to wire...it's typically the ones that have the chip thingy in the keys to prevent theft.