I don't know how much of an upgrade it is but I have a couple of those GTI
antennas that they put on Golfs and Passats.  These antennas are normally
mounted in the center of the roof in the rear of the vehicle and they come
with really long wires to allow this.  I have seen one of these on a Vanagon
(the guy filled in the hole in the nose) and it looked cool.  These are $50
for the kit.

Thanks,
Ken Wilford
John 3:16
www.vanagain.com
Phone: (856)-765-1583
Fax: (856)-327-2242