Being that the antenna and the coax have different impedances the coax actually modifies the impedance shown. This can make the impedance appear as less or more. This does not change how the antenna functions, if anything it simply hides a potential problem or make it seem like it is not as bad, but can also make it appear worse.
I have a similar band setup on my radio, and it is a common system. I am running a Galaxy DX55HP, and have seen this setup used on many different radios.
As far as the coil is concerned you shouldn't need one on a 1/4 wave antenna such as the one you are running. If it is the proper length the capacitance and inductance should cancel each other. Adding an inductor of any kind will throw off this balance, as well as shorten the length that the antenna needs to be to be resonant. I am curious what an antenna analyzer would say about the resonant point of the antenna before and after this coil was added.
Also note, an SWR match does not mean an antenna is resonant. While most antennas are designed to keep these two points close, it is possible for an antenna to be resonant at a wildly different impedance than 50 ohms. Tuning to resonance will net better performance than tuning to an SWR match.
I believe you, you should recommend it quit smoking... horrid habbit... 
I see by previous posts on this and other forums that you did do research, at least on some things. That is more than many people do before running an amp. Amps can be expensive, and there is a lot of misinformation pertaining to them. They are also among the first places people go to increase their range when it should be their last. You at least did other stuff first.
The rating for the Wilson 5000 is based on the coil within it, not the coax used. Look it up, you will see that it is not rated for near that much power. It should be able to handle that amp though. I wouldn't trust the RG-58 myself either, unless I happened to know it was mil-spec. Even then I just don't like RG-58. LMR-400 would be overkill for the power rating of your amp I think. That being said, go for it.
Most people think that the whole car acts as counterpoise, they see the DC grounding used in most cases and think a ground is a ground. What many people don't understand is that a ground at 27.x Mhz (cb frequency range) is very different than a DC ground. For example, on my Maco V5000 base antenna there is an electrical short between both conductors of the coax when using a DC measuring tool, however at 27.x Mhz this dc ground connection acts very different, and in fact is part of the tuning mechanism of the antenna. In your car there are many DC connections between the various metal pieces, and in some cases no real connection at all. Non-conductive things like paint get in the way. What RF bonding does is make the whole of the vehicle act as one unit for the counterpoise, rather then several separate components that all happen to be together. It also gives you a better capacitive coupling between the counterpoise and the actual ground lane for the antenna, which is the ground itself.
Ahh yes. I have seen you on several other forums, that is where I may have picked that up from...
The DB
