[Legion5]

I'm looking for the best possible upgrade to the Hi-Fi audio system without tearing apart the car. The primary things I'm looking to improve are the bass response and the clarity.

Cost is up to $5,000 and I don't want it to look modified and I don't want to start fabricating custom enclosures etc. The car needs to be easily returned to stock in less than day of work in 3 years so no permanent modifications.

I've seen most people recommend first replacing the stock amp and adding the EPS (enhanced premium sound) speakers, and then replacing the floor subs. I'm a bit new to this but not car audio in general so fee free to advise me on the basics.