If you like good CD to demo your vehicle with try these:
Sarah Maclachan(sp?)- most of her CD's are quite good and have a wide array of musical taste
Craig Armstrong-done many songs from soundtracks that you've heard but never knew the name to, awesome CD is Plunkett and MacKlea, has orchestra pieces with good low bass rumble and fast moving string sections. All of his CD's are good
DMB-Stand Up- very good CD with alot of good songs to demo. Different sounds too
311-Transistor, this is probably my favorite CD as its in HDCD, which has a more true midbass and bass sound to it. Very good sound
Perfect Circle- awesome sounding songs, great bass lines to them that can really work your speakers out.
Honestly, for "most" people any CD will sound good as long as it sounds right. I've found after going to alot of shops who say they have "good" sounding setups that they sound good until you turn the volume up and it loses it and the music loses its focus. While I may not the loudest pounding bass or the most wrenched screaming highs, i will say I have the best SQ. For me SQ means that at any normal volume and high volumes the overall characteristics of the system don't change. I've sat in some of the DEI's reps cars and it sounded nice until you turned the volume up and the highs killed out everything and then you'd feel the bass from the subs, no mids. If you want a good sounding setup IMO make it so at even the highest volumes you'll go the system is balanced and focused and really the music as a whole got louder, just my .02$.