What's the most cost efficient way to improve the sound system of the base stereo?

I purchased a 2007 G35x without the premium package, and have been disappointed with the sound system. From the posts about studio on wheels, I have no regrets about my decision to get this car for well under $33k, but would like a low-cost (ie under $600) upgrade to make the sound quality better. I figure upgrading the speakers would get me the most bang for the buck, but I have no idea where to start, having never switched out the speakers from any car I have ever owned.

Any suggestions???

2007 G35x sedan/platinum graphite/graphite

 

components for the front, a sub, and 2 amps will clean it up...components will depend on the type of music you like i like the jl zr's or xr's...

 

CDT components powered by a aftermarket amp

 

if you arent looking for a HUGE amount of bass, i have designed a few systems that fall int eh range of 1500 dolalrs or less, labor and materials for the G35 that IMO sounds excellent:

this is an example: if you dont consider the headunit, whcih either you can use the stock and put in a line driver, or a decent 250 dollars headunit...

https://g35driver.com/forums/audio-video-electronics/128938-perhaps-my-simplist-g35-install-date-pics.html

basically:

DLS CA51 5 channel amp: $400
DLS MS6 comp set, in doors , tweets in kicks, run fully active off the CA51's front channels: $275
elemental designs 11kv.2 10" sub: $125
4080box: $300
labor of amp rack, dampening of doors, wiring etc: $300
line driver: $100

add a heaudnti nstead of the liner driver...and you end up at the most with 1650

b

 

Thanks for all of your help, guys. Sadly, though, some of your suggestions and terminology (ie, CDT components) are over my head. What I would like to be able to do is to go to a bestbuy or similar store and pick out some speakers or other peripheral components that can replace the stock speakers without the installers having to muck around in the car too much.

What brands (please don't abbreviate) do you guys like? As far as the music I listen to, it ranges from jazz to classic and hard rock. Clear and sharp bass is very important to me. The base G stereo seems to distort heavy bass (Zepplin's When the Levee Breaks) as well as failing to capture all of the nuances of less "heavy" pieces of music.


If you can believe it, I had a used 1985 Lincoln once upon a time which had better sound quality than the stock stereo in my 2007 G, even though it was 8 years old when I had it..

 

do not go to best buy to stuff...go to a stereo shop, you will be happier at the end