It's definitely just the base radio. What do you mean speakers are "full range?"
I am going to just upgrade to high quality speakers, I hope that makes a nice difference and if so I don't think I'll spend any more money after that.
Full range speakers mean they produce sound from low frequencies to high frequencies, and not very well sorry to say. (If you've ever heard a well set up car audio system you'd understand what i mean.)
Upgrading speakers will be a plus, specifically coaxial speakers with built in cross-overs.......don't ask it would be a long discussion.......they will sound WAY better!
If you like your stock head unit, and it does all you want, by all means don't change it! Most car audio stores sell a bunch of un-necessary gear for the average person. You will be very happy with new / better quality speakers!