I’ve heard similar complaints from newer vehicles where the factory “premium” systems don’t always live up to expectations. A good installer should be able to improve the sound without turning it into a bass-heavy setup. I’d look into upgrading the front speakers, adding a quality DSP amplifier, and possibly improving sound deadening first—those changes usually make a much bigger difference than just adding a subwoofer. Hopefully someone local can recommend a reputable installer in the Las Vegas/St. George area.