Here's my $0.02:
I just got back into C.B. two months ago, after 15 years away from it, and I'm learning more all the time from this here forum. If I had my setup to do over I might run even better components, but I digress.
My current setup: Uniden 980 with an Astatic 636L mic connected to a Wilson 2000 Trucker on a 5" magnet mount on the center of my 2000 Cadillac's roof. My clear, good, consistent results are: 9-10 miles on SSB mobile to mobile, 23 miles on AM mobile to base station with tower mounted beam antenna pointed my way, and 2-3 miles on AM in front of me mobile to mobile (on the interstate).
After initially installing my Wilson 2000 Trucker mag mount it took only a few minutes to adjust for my best SWR (1.4 on channel 40, 1.2 on channel 1) simply by adjusting the height of the 49" whip and tightening the two set screws.
No doubt, there are better C.B. setups to be had, but, I'm pleased with the performance of my mobile setup and I've gotten good reports far more often than not when receiving radio checks.
C.B. is great! The problem with C.B., though, is this: once you get started the tendency is to upgrade, augment, and push performance as far as you can.