I read this ^ earlier today and literally just got done and it sounds amazing!! I have a 2000 with a tape deck, followed the directions on the link in the previous post (#638) It cost me zilch, nadda as I had all the stuff already at home and total time with testing and running the wire through my dash took maybe an hour! Very happy with the sound quality as well! I was using a cassette auxiliary adapter and the first thing I noticed with the mod... noticeably higher treble and an amazing increase in bass, hands down sounds better than the CD player (in trunk) and even the radio.
I suggest if you have the older stereo with a tape deck to do this mod if you want good beats in your car!