06 saturn vue, amp, speakers

My warranty just expired on my VUE, hence it's now a science project. It's been a wile since i've messed with car audio and I really want to keep this project clean unlike my civic in high school. Does anyone know if it is possible to keep my factory head unit (it looks nice) and still have an amp and all that hooked up to it? My buddy back in orlando has a mazda hatch back and he did it and was talking about some type of "converter" does anyone know what he is talking about and if so where can I buy one? Also I am not interested in buying a yellow top for the time being, or a beefed up alternator, so I think I will be rolling w/ one amp. Does anyone have any suggestions for 6.5s that will be loud enough un-amplified that will not be drownd out by two Kicker CVR 12" DVC and a kicker amp? I like bass as much as the next person but I want to here what jeezy and game are talking about from time to time.

Thanks for all the feed back! I got it figured outsam sneaky