Newbie question cobra 29ltd modified

[Bobalou]

Hi guys I hate to be the type of person that joins a site and immediately asks a question but I've been searching and cannot find an answer so I thought maybe I might have some luck here. I have a beefed-up Cobra 29 LTD Chrome that I was running at my tri axle for the past four or five years I recently upgraded and placed the cobra into my show truck. It's a 2002 Chevy Silverado custom on air ride. We recently decided in my club that we were going to start using Cbs for navigation purposes with our convoys to shows. The problem that I'm running into is I installed my radio and I cannot get my SWR down. New fire stick antenna I know not the greatest, new coax, new mount. The mount is bolted to the headboard of the pickup truck and then I ran a ground wire from the mounting bolt to the frame rail. This radio work amazingly and my tri axle both a 2016 Peterbilt and a 2019 Kenworth. My show truck does have a stereo in it but is currently not powered on is there any idea what could be causing me to not get low SWR? Is this going to be a huge concern?

Thank you for reading and again sorry I don't like to be the new guy immediately asking a question

Bobby

[AtLarge]

What is the length of the Firestik and how much is above the cab? Did you clean the frame mounting point before you bolted it up cause if you left the crud, rust, etc. your probably losing connectivity.

[Bobalou]

About a foot above the cab, and yes cleaned it twice actually lol.

[AtLarge]

Possibly too much reflected interference would be my guess. Need to get higher and or farther from the roofline.

[Bobalou]

Thank you for the input, would a Wilson whip change this do ya think?