I run the Buick Regal's Concert Sound II setup with different speakers. It uses 5.25 in woofers in the doors and 1 in tweeters in the stock locations in the dash. In the rear I have 6x9's with adapters, and 2 10 in subs. Powering the whole setup is a 500 watt amp for the subs and a 75x4 amp for the satellites. I don't have a pic of the grilles on the speakers just yet, but here they are in a test fit after I cut the doors for the grilles and installed the speakers to the door frames:
As for what speakers they are, they are Phoenix Gold speakers I got off E-Bay. Right now, I am not too impressed with them, but for $65, I don't have too much room to complain either. They seem to sound too "muddy", if that makes any sense. It may be the deck, but I dunno yet.
I'll also say that it depends on what kind of music you like to listen to. If you are into booty music, you will want the most ridiculous set of subwoofers (preferably multiple sets) you can find, powered with a 5,000,000,000 watt (RMS) amp, and augmented by some sort of other speakers to play the range of sound above 100 hz. :lol: If you like music with more range than that, you will want to concentrate mostly on the satellites and buy a low end sub with a modest amp to power it. The head unit is VERY important. A poorly chosen head unit will never let the rest of the system live up to it's potential. So, don't just buy the cheapest CD player they have at Wal Mart. Get a mid range model from a major name brand like Pioneer, Alpine, JVC, etc. Also, get one with a separate subwoofer channel ( 6 pre-outs), and a USB input on the front. This is important as it lets you use either a flash drive or a MP3 player to store your music instead of having to carry a bunch of CDs. CDs and cars are not usually a good mix as the environment typically damages them in short order. Plus, an MP3 player will let you store an amount of CDs that would take up your entire back seat in a device smaller than 1/4 a CD jewel case in size. I have a 4gb iPod (I bought broken and rebuilt), and it probably stores 40 whole albums on it. You also want a built in equalizer that will let you tailor the sound to the car's acoustics, and the drivers you have chosen.