Tune Up

I recenly went to a CB shop and they offered CB tune ups. I asked what this was and was basically told they make the radio put out more power. Take it from the regulated 4w to whatever they can get out of it. I was just wondering how you do this without putting some type of amp on it. I know you you used to be able to by CB amp way back when, but I doubt you can anymore, legally anyways. Anyone have any idea on how to get more power out of a stock CB?

you can buy what they call a linear i have one on mine and it has high low or off i can talk all over the us with my 2 10 foot whips and my linear and you can also get more power added into your cb they both work but i would rather have a linear