[kingdaddy]

It is true the air bags won't change the manufacturer's capacity ratings of your truck because the limitations are very likely going to be something other than your rear springs e.g. your combined weight rating, rear axle rating, tires etc, etc.
Since it is aftermarket, not factory installed, neither the truck nor the air bag manufacturer are comfortable allowing a change to official ratings. Totally understandable, but my point was simply to point out that the bags actually do increase your load carrying capability from a practical standpoint because they increase your spring rate which result in your truck being able to remain level while heavily loaded.
It does seem like everyone is pretty happy with how they work, lots of people seem to like the Timbrens too.