2013 LTZ audio/speaker newbie questions

Hi all, I am interested in getting started with upgrading the sound system in my car. I have begun doing research for the past few days, but I believe for my use case I might get better help on this forum. My model came with the Bose speaker system on it (if that matters) and I noticed that at higher volumes the bass does distort a bit, and the quality, while fine at low volumes, leaves some quality to be desired on some of my more acoustic songs.

My main question is simple, I want to know if I could get any minor improvements with a simple speaker upgrade/replacement without having to figure out amplifiers, crossovers, etc. And if anyone who reads this and has a 9th gen impala has any speaker recommendations that I could just plug & play and enjoy better sound with at a price of ~300 to 400 dollars. I'm not looking for any crazy improvement. I also want to keep my current aftermarket (relatively cheap) navigation head unit.

Any tips, advice, warnings are appreciated, as I'm still new to audio systems in general, but I also have no problem doing a little wrenching.