You need to get a wire harness adaptor plug that onto the wire harness for you car that went to the factory radio, wire that to the harness for the new stereo. Now you will not need an amp for the speakers, but it will make them sound a little better, do not amp factory speakers ever though, that will blow them. The last thing is this, Sony is going to give you poor sound reproduction in your car, which is why amp is only going to help a little bit. If the amp receives a poor signal that is what it will process, a bad signal equals bod sound.
