If you do go with a popular namebrand aftermarket headunit, it should be enough power to run all 4 speakers. The assumption is that all want is to have some decent sounding tunes while driving. If you decided to add some subs, then you'll have to get an amp.Rockenreno wrote:If you don't have a factory amp back there do you need an amp to run speakers back there or will a new headunit suffice? If anyone recalls, I'm planning to put in 4 new speakers (I have 2 right now-- up front, but I just bought a rear deck lid with speaker holes) and a new headunit (to replace the tape deck I have). Do I need to get a new amp? Thanks.