Thanks, that's what I had hoped. I had initially thought that the nav system controlled some of the stereo functions, making me worried that it wouldn't be possible to install the empeg.

A couple more questions. Where in the "circuit" does the amp go? directly after the empeg? The nav?
How much power do I need in the amp? I saw one at Circuit City for about $80. It appears to be all I need. The factory head unit has 80W of output, and I believe that there are 4 speakers and 2 tweeters (although there may be 6 spekers. it's a long vehicle).

Thanks for all the help! I only had 3 things keeping me from buying an empeg. Getting a car (very important), getting the money (on my way), and getting it shipped (out of my control :)). Now I need: the car delivered, my paycheck to come in, and the empeg to start shipping.