I agree with, Intgr8r, DocRisk. That one's a little too flashy for my tastes. I thought the whole reason for getting a stubby antenna was to make it less noticeable.
I remember people mentioning back on z4um that the antenna is more for AM whereas there is a strong FM receiver located somewhere in the trunk. So the stubby antenna does slightly reduce your AM reception but doesn't really affect FM.
Someone mentioned to me that whichever receiver is picking up the better FM signal (either your trunk or your antenna) is the one that is used to transmit. Make sense?