If your replacing it with an aftermarket unit all you need is to get a wire harness to plug into the factory harness that is left after unplugging the stereo and slap the new one in just like any other car. The security feature that locks the radio is only on the factory one. Also you'll have to figure out what you want to do with the trim since the factory radio has a unique fit to it... so there will be unpleasant asthetic propertiesso since we are on the topic of head units. Is there anything special to changing out a head unit on a civic. The code thing has always been somewhat of an intimidatation factor for me changing it in mine. Is there a diy faq or can someone explain