It takes 10 times the power to raise your signal one S unit. So 40 watts will get you putting out one more pound and burn out your finals, why? Have the radio aligned so it is running on frequency and its running at the legal limit of 4 watts (the FCC doesn't care about CBs really). The only way to really put out is to have a good antenna. A cheap radio on an awesome antenna will smoke a tuned up radio on a shitty antenna. Excessive modulation also will not help you to put out better in the distance, you'll still sound garbaled. All you need is a decent radio running right on frequency with a good antenna.
"An old Blazer never dies, they just... rust away."