I just installed a Cobra 19DXIV 40 CB with a 18' coax and a Firestik II 3' antenna. I have a tailight mount bracket and the stud is grounded on the bottom and has no continuity from the antenna to the frame. I am getting 2.25:1 SWR on channels 1 and 40. On channel 20 I am at 1.5:1. What is the general consensus for 2.25:1? Is that an acceptable SWR for a Wrangler. Any suggestions of input on making it better?