I've found in recent years DC makes pretty decent radios/speakers for their vehicles. My last vehicle was a Dodge Dakota PU with am/fm/cd which sounded good too me. So, to my ears, listening to music with stock speakers would be okay. But, if you want the very best sound, then install after-market quality speakers (with good bass woofers built-in). Think this would be your best route to go for an upgrade at the least cost. If you replace your stereo/cd, you leave yourself open for the thieves--but, no self-respecting thief will break into your PTC to steal a DC stereo to try and sell to a "Chevy or Ford guy".
When buying my GT I spent the extra $150 MSRP to get the optional AM/FM stereo with the 6-disc in-dash CD player because it also included 6 premium speakers which I wanted in order to get the "best" sound.
Good luck.
"Other than driving my Inferno Red GT Turbo
I'd rather be fishing
."