Any way to update stock audio system to sound better / louder

It's not simply about changing the speakers it's about getting a more sensitive speaker. You want something with a sensitivity in the 90s which basically leaves you with Kicker, Hertz and a couple other options. I have Hertz for the front four speakers and love them. I had Kenwood in the Camry they were nice too. Much better than factory.

 

I have a 2017 Four with the JBL package. I replaced all the speakers with either infinty or JBL's. I had to get a DSP because the head unit only sends a bass signal to the Woofers in the front doors. I bought a small amp to power everything. It has to be less than 30amps. This way it will not affect mileage. I spent a lot of time with Crutchfield to figure out my needs. The car ROCKS now!! The sound stage is where is it should be not at the steering wheel. Next step is a small amp-subwoofer combo in the back. I went on ebay to see just what JBL speakers are installed by Toyota. They are complete garbage. it was about $400 for all the equipment and another $400 for a professional install. Turned out to be way more than i had planned but its worth it IMHO.

 

Just added a small 8" Sub tube in the back pointed at the trunk. Wow the car ROCKS now. Loud enough but not enough to rattle the windows and plenty of bass. It sucks that it cost me $1000 to upgrade but it was worth piecing it together over time.