So since I was a kid, my favorite place to listen to music is in the car. I've spent SOOOO much money over the years on custom sound systems and enjoyed the fruits of every penny.
The Accord Sport's 8-speaker system is not bad for a stock system, but not even close to what I'd consider adequate for my needs. I made a few simple changes:
I replaced the front mids and tweeters with Focal Expert PS 165V1 separates. I love Focal's stuff. Just terrific imaging and separation, but they need some power to make them sing. And just looking at the car, they fit right into the stock slots. No visual difference.
We added a JL Audio JX400/4D amp on the ceiling of the trunk to power them.
Then put an older Infinity Basslink twin subwoofer I used in my last car in the side of the trunk.
We also installed sound dampeners in the ceiling and bed of the trunk, and in the front door panels, to reduce vibrations and channel the sound into the passenger cabin.
It sounds absolutely stunning. Total bill for equipment and install was about $2,000 and it's worth every penny.
On a side note, if you have a system that will let you hear the difference, I strongly recommend Qobuz for hi-res audio streaming. Put it this way, the best quality Spotify ever streams at is CD quality. That's the worst that Qobuz ever streams at, and unlike Tidal, you don't need a MQA unfolder to fully benefit from their hi-res tracks. The one bummer for now is that Qobuz will not stream via Apple CarPlay, it will only play downloaded music. They said they're working now on a version that will change that and make all functionality available via CarPlay. But it works fine streaming in the car via bluetooth audio.