This was certainly true for me. I have a 2013 Grand Caravan with the stock 6-speaker setup and a couple of years ago I got a good deal on a Pioneer head unit and boy did it make a difference. Between the upgrade to 22 watts rms per channel of power compared to the stock radio, and the 13 band eq, the cheap *** stock speakers sound really good now. People have got into my van and asked me when I put in a system and when I tell them everything is stock except the radio they can't believe it. I'm getting ready to upgrade everything else now, but with the exception of it lacking a little on the low end punch, the setup sounds really good just from a HU upgrade.