I just installed my Sirius unit and antenna, my antenna is alittle bigger than a half dollar and very slim, I put it in between the two stock Mach 460 Subwoofers in the back seat. I get excellent reception and I live in the boonies.

 

I put my antenna on the trunk using 3M automotive double stick tape, car manufacturers use that stuff too. I got the antenna painted from www.colormatchantenna.com. I like listening to Maxim. So anyway try double stick tape no one will ever see it.