Good idea.

i purchased the ctek from amazon for ~$50 and it has definitely extended the life of my battery. it also "cured" the radio mute problem, which seemed to be related to the aging battery.

http://i160.photobucket.com/albums/t...e4bab81f31.jpg

i agree with jeremym, replacing your battery is not a bad idea if it's the original oem and is >5 yrs old. however, this may or may not be the source of your radio issue.

btw, a couple of related posts that might be of interest to you:

my original post ~1 year ago with another xoutpost member experiencing similar symptoms/solution
http://www.xoutpost.com/bmw-sav-foru...w-gremlin.html

battery replacement discussion
http://www.xoutpost.com/bmw-sav-foru...save-mode.html

best of luck. :thumbup:

update: I finally decided to drop it off at the BMW dealer and they replaced the amplifier, said it was shorting out. Audio is working perfectly now.