Can you hook an amp up directly to a factory head unit, or is there some kind of special way that you have to wire it in?

 

Yes you can add an amp to the factory radio. Look for an amp that has speaker level inputs along with line level inputs. The line level are for the RCA type plugs you'll find on many aftermarket radios. If you get an amp with both and you decide to upgrades the head unit to one with RCA jacks it'll be that much easier. I just ordered an amp and speakers for my 09 and I'll be using the factory radio. The amp has line level and speaker level inputs. Go to crutchfield's site and check out some of the videos on installs.

 

You can also get line inverters to take you speaker level inputs down to preamp level, and you can tune them to your speakers and amp. I tried wiring mine with the high side wires on my Alpine, but didn't like the harshness, so I put line levelers in there and it sounds smoother. Just a thought.