Welcome to the group from a fellow D/FW'er.
Make sure you mount it on the rear roof. I helped another CEG'er (who shall remain namelesss :p ) figure out the high-pitched whining coming from the front of the car above 60MPH was his antenna. Turns out he mounted the antenna on the front just above the front windshield.
Shaving the old antenna should be easy, it sounds. The antenna wire that goes to the trunk might be long enough to run inside the C-pillar, inside the car. This also depends on what kind of connection the new one has.
Are you up for coming to a DFW meet this Saturday? Check out the DFW section for details.
