The torque arm has no effect on ride height or load carrying capacity, neither do the shocks. You need to increase your spring rate, or add an assist such as the air bags mentioned earlier.

 

But shocks *do* affect ride quality/handling -- part of their job is to control the springs...

 

Right, not disputing that fact at all. Better shocks will have an effect on spring rebound, but won't change how much weight the car can carry. The car would sag just the same as it does now. Air shocks can adjust the ride height and load capacity, conventional shocks can't.