2015 Freightliner Cascadia Antenna Issues

[jfogle01]

Alright group, I need some advice. Here's the background:

...2015 Freightliner Cascadia,
...Wilson 2-bolt plate w/post made for Cascadia mirrors,
...Standard 2-bolt antenna mount,
...Wilson 2000 Trucker antenna,
...Standard antenna lug connector,
...9ft mini-8 coax - new,
...Cobra 29 - peaked & tuned w/echo and a hi/low deadkey added,
...Older RK56 mic w/capasitor swap

Now that that's done, on to my problem. After installing the bracket to the front two mirror bolts on my driver's side mirror, and running a separate ground wire from that mounting plate down to a solid metal bracket located under the hood that is grounded directly to the frame, I am unable to get my SWRs below 2.5. That 2.5 was achieved after angling the antenna approximately 45°, thereby moving the whip of the antenna further away from the body of the truck. I am at a loss and could really use some help or advice. Thanks guys and gals!