Wouldn't bother to much with dealer/manufacturer upgrades. They tend to just be louder with more clarity which doesn't equal Sq (sound quailty)

Decent sound quality (audiophile) can be achieved in a car environment.

It doesn't come cheap though and is often destructive to the car meaning major modifications and endless hour's of install and set up. Especially in modern motors...

I run a decent Sq sound system with a infinite baffle sub idw15 made by Image dynamics (90 's kit not the modern crap) audison components in custom baffles and tweeter a pillar builds. All run off of some of phoenix golds top line 90 ' amps (route 66 and zx series) and a pro audio processor (this is needed to tune the sound to compensate for the poor environment of a car) and a top end denon head unit.

It's not loud but sounds so sweet. All built myself taking many hours of install and even longer to tune correctly.

It's not high high end St all rwally either but a good daily listen. And probably not worth the money time or hassle for the average person to be honest.

Check out talkaudio if your serious about good sound in a car.

Just my 2 pence!!