I was randomly Googling when I came upon this program..."San Andreas Radio Be your own DJ" which lets you rip all the commercials, music,Phone and DJ chatter right off the PS2 GTA SA DVD.
I tired it by
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All I did was insert the PS2 Disc into my DVD drive and opened the program.it then read the disc and loads all the music files.But there is more!The Program lets you mix the audio files and you can save it as a .cue file to burn to make your own gta soundtrack mix!!!
I took a screenshots
EDIT:You can also save each music file(Dj chatter,Ads,Music) as a standard .wav sound.
The Software can be found at:
http://www.tinyted.net/eddie/SanAndreasRadio/