Our CB is dash-mounted and a plain ol' brand-name something-or-other (brand isn't all that important since they all make the same power, etc). Radio Shack is fine, so is Cobra, and so on. The antenna is far more important, and like so many things in life, bigger IS better. The radio must "see" an antenna that's a quarter wavelength long -- there's your 102". Because lots of folks want a smaller antenna the manufacturers put in loading coils (the lump in the bottom or middle or top or wherever) to make the effective length correct. But -- the coil isn't nearly as effective a radiator as a full-length wire, so coils lose some of that 4 watts -- that's why shorter antennas don't work as well (usually) as full-length ones.
But also make sure your ground system is above reproach. Good grounds are vital -- the radio signal needs the full circuit, just like the starter motor and the gauges on your race vehicle. This may be one big reason why our setup -- a bottom-loaded antenna, about 4' long, permanently mounted (with hole drilled in the metal!) in the center of the roof works well -- better than the same antenna might if it were on a magnet mount. I usually hear the CB from the Salt while I'm still at the motel in Wendover. I can talk to the race track by the time I'm on I-80 -- just past Car Quest.
Finally -- SWR = Standing Wave Ratio. It's a measure of how much power is being "reflected" back from the antenna to the output stage of the transmitter. Setting it requires use of an SWR "bridge" - a measuring device that most folks don't own, but most radio shops DO have. I've got one -- and keep thinking about taking it to the Salt to lend to folks, except I'd probably end up spending the best part of the week checking and setting SWR. Anyway - you want your SWR to be as low as possible. Anything under 3 to 1 is acceptable, and the closer to 1:1 you can get, the better. SWR changes with frequency of the transmitter -- that is, it'll read differently on Ch.23 than it does on Ch. 1, so set the SWR to minimum on or near (don't cause interference to others by tuning and testing on the channel that's in use) your chosen frequency (at Bonneville it's Ch. 1 and Ch. 10 as a secondary channel). The SWR is changed by adjusting the length of the antenna -- kinda hard to do if you want to make the antenna longer, so it's common to have a few clips or bobby pins handy to put on the very tip of the antenna during testing. Shortening the rod is easy -- but hard to make long again if you cut too much off.
There's your quick primer to SWR and other CB stuff. (I've been a radio ham for 43 years -- have played with antennas and SWR for all of those years).
