Having your C.B. "tweaked and peaked" is kind of a waste of time unless you are running it in tandem with a power amp. Most C.B.'s (especially Cobras) are already tuned, out of the box. All this garbage about tuning antennas, etc, .. is just that... garbage.
I believe in setting your SWR's (Which is VERY SIMPLE) and just making sure you aren't "over-modulating" ... some guys think this is cool, but it really doesn't sound that good. You can open up your C.B and turn up the modulation, but you kind of want to be careful.
Have a friend sitting close by with his C.B on so that he can hear the difference. A little added modulation is O.K... it's not gonna make much of a difference distance-wise, but it will sound different.
If you really want a different "sound" just buy a talk-back speaker and crank it up to where it distorts without any feedback.
You are only going to reach "so far" with your stock C.B.
A "tune-up" around here is around $25.00 and it isn't going to do anything drastic. Most guys just want to add some echo and a little modulation. You can actually do that yourself, very easily.
Just listen to the Bigrig "Rolling C.B" interviews on Youtube. That's about what you will sound like.
