Mine works okay. I tried using an AUX inout converter, but it doesn't work with the 6-dic CD changer. My first FM modulator had poor bass, but I swapped it out with a better one (don't recall the brand, got it at Fry's). I recommand the Belkin auto kit to connect to the modulator so you can use the audio outputs instead of the headphone jack. I have a Creative Nomad Jukebox instead of a iPod and can only use headphone output with the volume at %100. Not the best way, but it does work.
With the iPod set on the "jazz" preset and the volume at 100%, I get CD quality sound from my FM Modulator, which is the JVC model available at Crutchfield.com. Ragingfish installed it at the Ohio Rally. Including the two necessary adapters for the Vibe and shipping, the whole order was $55...not too bad. A whole lot cheaper than what I was quoted at Circuit City and Dashboard Audio.If you check out the "Kari's iPod Setup" (http://forums.genvibe.com/zerothread?id=11993) thread, there are photos and more detailed info. I can't tell the difference between the iPod and a CD when I've got the iPod's equalizer tuned right...I'm very pleased.