I have a Pioneer AVIC D3 head unit in my 00 S4. It works great, dvd, nav, ipod, XM, but the regular radio is really really fuzzy or gets no reception like the antenna is not hooked up. When i move around my XM reciever on the dash i get a little better reception. Any ideas? thanks.

 

I have the same problem after installing a new Alpine HD radio deck. I think the stock antenna does not work with aftermarket stereos. Likely what you are going to need to do it get a new hidden antenna (since there is no place to put them on the outside). I've been doing a good amount of research on this topic and have a few good antennas but the links are saved on my work computer. I'll try and post them up on here for you tomorrow.