Have you had anyone tune it? What about the speakers, were they voice matched and their requirements matched to the output capabilities of the head unit? Many aftermarket radios assume you are using an amplifier. I'm guessing you didn't install one. If you don't match components then you won't get good sound. That's why high end setups cost so much. There's no real plug and play off the shelf answers. One setup may work good in your buddy's truck but sound terrible in your car. Research, research, research. A properly setup up "cheap" system can easily outperform a more expensive high end setup. It's all about matching components and capabilities and being sure that each component is operating within its ideal range.
Think of it like your camper. Did you just order one on the web and hope it would work? Or did you match it to your truck, your situation and your budget?