I agree that the standard radio is decent, however, I plan to use one of these products. (the Trunk-lock)
http://www.pac-audio.com/products/pr...t%20Converters
I have used this in my girlfriends car, and her sound quality jumped as well as the level control opposed to just using the speaker inputs on the amp. Also, this product can run ~$30 online.
Easy install, low cost, small size. What more could you ask for? Hope this helps.
~Tony