Need help with what to buy.

Ok, my girlfriend wants new audio system in our excursion. She loves how the GM vehicles with Bose and Monsoon systems sound. I've installed plenty of systems in high school for kids, but all that was a sub and amp. She doesn't want that overwhelming bass from just a sub like kids cruising and that's all you hear. Any recommendations on what to go with. Already have a double din headunit just looking to upgrade speakers etc. Thanks