inconsistent range scytech rs5000

Hello, I'm having a strange issue with the Scytech Galaxy RS5000 that is installed in my 2005 Chevy Silverado 2500HD. The bypass module I'm using is the XK01. The range seems to be very inconsistent. Generally the colder the temperature is the less range I will have. This occurs with brand new batteries in the remote 2 way remote. Sometimes the range will be so bad that I have to stand next to the truck to get it to start. I have the antenna mounted on the center of the windshield just below the tint line. My company designs two-way radios so I do understand that range will vary to some extent depending on many factors. What troubles me is that sometimes it gets so bad I have to stand next to the truck. I called Scytech and explained that the range gets worse in cold weather, they told me to put the antenna under the dash. I have not tried this because frankly it seems to make zero sense. They said it would stay warmer there. Does anyone have any idea as to what might be causing this range issue? Thank you in advance!

Did it come with a 1-way remote...Hows that range...?M.E.C.P & First-Class

Go slow and drink lots of water...Procrastinators' Unite...Tomorrow!