powered by an amp correct? I always thought that the head unit just puts power into the speakers and the the amplifier puts power into the subwoofers, am I correct?
Nah. When you hook it up right, the speakers and subwoofers are powered by the same amp. If you really want some more noise, then you need more than one amp and then you can pick and choose which one powers what part. That is the simple reply. You should seek professional help if you want to turn your car into one of the ones that impress/annoy the rest of the people around you.