2004 A4 1.8T originally with Concert II (1-din headunit , non bose)

I don't have that little shark fin on the back of my roof. Is that for XM?
Well on the back of the headunit there IS a standard stereo antenna wire running in to the headunit. Where does that antenna go? I ask this because I have swapped my headunit out with a Pioneer AVIC-Z1 and I just notice that my reception sucks. Sure sure it doesn't matter cuz I have iPod and XM unit, but hell I wanna know :P

Thanks!

 

built into the rear window

 

not sure how much the later models changed but probably not that much on the wiring so im guessing they still all go to the D pillar/rear windshield area