If you are planning on adding rears, you have 2 choices - an OEM kit and one named PNP. The PNP has better speakers but I found this out after I bought the OEM. Contact Harvey at
harveypnp@comcast.net for details. Prices for either are in the $250-265 range. I luckily bought my OEMs for $200 on an ************************************************************ closeout. As MN said, you will need to connect them to the radio. They will fill out the interior sound but won't knock your socks off.
Once you've had them in for a while, be prepared for the next mod -- that 6 chl amp you were originally asking about. Mine is in the mail. This amp will allow you to run the rears with MORE POWER.