I was having the same problem with my iTrip so I went right to Griffin and they gave me something to try. It definitely got rid of the static.
Here’s what they said:
You might have a bad transmitter, but before we assume this lets try a soft reset. Sometimes the iPod has trouble communicating with third party
devices, but we can fix that with a “soft reset.” With the iTrip plugged
into the iPod and the iPod turned on, hold down the ?Menu? and ?Select?
buttons until an apple appears in the screen. Then you can let go and wait
for the iPod to restart. After it restarts, try playing a song and see if
the iTrip works.
You still have to have the iPod “really close” to the radio, compared to my brother’s old version that makes it 4 feet and the volume is lower than I’d like because when I’m done with the iPod I’m blasted with FM.
I’ve contacted them again about the above issues. If I find out more, I"ll let you know.