At one time you were able to give the radio repair shop guy an extra 20 at the local truck stop to boost them up from stock, of course you look like a red flag to the FCC.
That is not a thing of the past. I still peak and tune, upgrade, and all the good stuff. Just make sure if you have it done, take it to a shop that is qualified, not a snip and hack shop.
As far as the magnetic antennas go, make sure that it is a no-ground-plane antenna. You will get your best results from a conventional mounted antenna. If you have an antenna that requires a ground plane, which most do, and it is not present, you will not get out more than 2 miles from your ride.
On the antenna subject, yes 102" steel whips are the best for range, especially when setting still. When in motion, the steel whip will loose some of its efficiency, but will still out-perform other mobile antennas. If you go that route, make sure that you have something to insulate the whip from touching any part of your vehicle. At the time it grounds out, you do not have an antenna. That is why you usually see a tennis ball slid over one where it may make contact with the vehicle.
Now for SWR (Standing Wave Ratio). SWR it the ratio between the power being transmitted and the power that is being feed back into the cb radio. Basically, it determines the efficiency of the antenna. The only part of your system that will will affect and can set SWR is the antenna. Your radio and coax both have a 50 ohm impedance. When you are setting the antenna SWR, you are trying to reach as close to a 50 ohm impedance as you can. The problem with high SWR is that all of your transmitted RF power from the radio does not get transmitted out of the antenna. What does not leave the antenna travels back into the radio to the final transistor. When that happens, that power turns into heat, and the more heat built up can burn the transistor (which most people call "blowing the final").
If you do not want to have the added issue of setting SWR, go with a fiberglass stick antenna, such as a Francis or a Firestick, that is non-tunable.
If anyone has questions about setting SWR, shoot me a pm or email and I will be happy to help you out.
It is correct, most stock cbs get about a 5 mile range, give or take, with a properly set up system. After a radio is peaked and tuned, take a Cobra 29 LTD CLassic for instance, it will typically modulate between 25 and 30 watts, depending on how wide open the modulation trim pot is turned to. If it is opened wide, the radio will usually modulate over 100%, which you do not want it to. It is best to have the modulation set between 90 and 100%. At 100% a Cobra 29 will typically modulate right around 25 watts with a clean signal.
10-meter radios are able to be turned up more than most cb radios. You can get 10 meter radios that can be turned up to 400 watts. The reason 10 meter radios are against the the FCC rules, is because they are considered dual purpose radios. They come ready to talk on the 10 meter band (ham), but can be converted to 11 meter band (cb). The conversion is not a difficult or lengthy process if you know what you are doing. Some just have a chip that is moved from 1 set of prongs to another. Other conversions that a resistor cluster that has to be removed. It just depends on the manufacturer.