2002 Monte Carlo - Stereo Wiring/Stock Amplifier PLEASE HELP :0?

To start, I am terrible with factory wiring. I understand the basics of stereo systems and new wiring, just not the original stuff.... I have a 02 Monte Carlo, and I just bought a new pair of Alpine component speakers to replace the front two stock speakers. I have noticed, however, that the front stock speakers handle primarily only mids and highs, and the rear speakers handle primarily bass. Is this just the stock speakers, or is the the wiring? Could it also be the stock amplifier? I want to get a full signal going to the front speakers if it isn't already so, so how would I do this?