I have a 05 Sonata and would like to add a new radio that supports mp3 cds and preferably an aux-in. I -LOVE- the stock speakers and they sound great. I simply want a new headend that will have the above features, but keep EVERYTHING else the same. What do I have to look for? I don't want to bypass the amp (it has one in the trunk, correct? or am I mistaken.) What kind of outputs do I need to have? Obviously I'd get a wiring harness for an easier install... I just don't want to have to bypass any of the factory equipment. Thanks