I never hear it while the music is playing. It's very faint when the volume is high and no music is playing.
I emailed indashpc once i saw this news posting:
http://www.indashpc.org/new/news.html#28
They sent me a micro chip to install in the board in place of the old one. They should have just made it programmable from through USB...
Anyways I haven't installed it yet because of my unit isn't very easy to get to.
So tell me... does yours work properly? The back button on my steering wheel doesn't change songs, and causes the unit to stop responding to steering wheel buttons. I have to the radio and back to the Ex to get it to work again.