Compustar 2WSS-AS Diminished Range

My 2WSS-AS has about a 1/8 mile range at best, with a fresh battery.  This is under multiple situations: Car parked in parking lot, me inside store; Car parked in my garage, me at the end of my street; Car parked in parking lot, me in office building...  I emailed Compustar about this and they suggested that I check to make sure that none of the antenna wires are pinched.  I checked, and they're not pinched.  The antenna is also mounted correctly: Top driver's side corner of windshield.  I can't think of anything else, but I don't want to resort to buying a new antenna just yet.  Anybody have any ideas?

Me thinks if compustar explains how to install their antenna's the way B94Sport says, it must serve a purpose.

I have talked to others who have it mounted in the same place and they're getting the advertised range - 1.25 miles.  Compustar claims it was "calibrated" for installation there...  Whatever the case may be, I'm going to keep it where they say.  Other ideas?