Originally posted by: Black88GTA
For speakers....MB Quart are high quality, but very bright (which some people don't like). Another brand to look at is Focal - even their "low-end" line is very well respected. I would really recommend auditioning anything you are seriously considering buying before actually getting it.
If you can swing it, get component sets, rather than coaxials - comps usually come with separate crossover units, and require you to mount the tweeters separately from the main drivers. This way, you can aim the tweeters at the passenger compartment. Treble frequencies are very directional, and if they are mounted in kick panels or other areas where they don't face your ears, you lose a lot of the high end. The downside is that these aren't usually "drop-in" installations - they require a bit more work to mount the tweeters, run the wiring, and find a spot for the crossover networks. It's worth it though, IMO.
For subs -
these are very well respected as excellent bang-for-buck drivers. They don't have the name recognition of RF, Kicker, etc. (mainly because BB, CC type places don't carry them), but every review of these I've read has been excellent.
EDIT: Some CD changers don't play nice with different-brand head units. If you want direct compatibility, I'd try my best to match the brand of the new HU with the brand of the changer, and make sure the HU has CD changer controls - many don't.
Is your changer stock, or aftermarket? Hard-wired, or does it use one of those controllers you stick somewhere on your dash? If stock...you may be SOL. My BMW has a Pioneer 6 disc changer stock, but I can't use it with my aftermarket Pioneer head unit. Turns out, the changer has a proprietary "language" that it uses to communicate with the factory head unit, which is not compatible with anything aftermarket (without an expensive translator adapter). They did this so that if you wanted a CD changer in your car, you'd be forced to shell out the $1,000+ to BMW for the option - not $200 + installation to Best Buy.