I use to install WX500's and the like when I worked at the Avionics shop up in Albany NY years ago.  The Storm Scope system has a very sensitive antenna.  Many items interfere with this system.  The company has a tool that maps the best location for there antenna.  One of you local shops may have a mapper.  You many have to lease a loaner or go to a service center.  If you are looking to do it on the cheep, move the antenna as far away from any motors, output antennas, and hi voltage(strobe lights) items as you can.  Try to copy someone that has had success with the same setup including AP servo locations.