From the Roadmaster Active Suspension website http://www.activesuspension.com/
"Roadmaster Active Suspension kits consist of a set of two very powerful,
variable rated, coil springs designed to support and assist rear leaf
springs with up to a one ton carrying capacity.Once installed, loaded
tension from the eye-to-axle mounted coil tension springs hold the leaf
springs in their original designed bowed position. When strain from load
or vehicle weight shift is applied to the leaf springs, the stabilizers
come into action immediately, absorbing the force of the load. Being
variable rated, the greater the strain, the more counter-assistance
force from the RAS unit.By introducing a powerful ‘load absorbing‘
spring steel coil system to rear leaf springs, RAS greatly assists the
carrying capability of the vehicle as stipulated by the manufacturers.
RAS absorbs the load that would otherwise cause bottoming out and
thereby provides the benefits of a more level and thus safer ride."
The suspension does not activate until load is placed on the leaf springs, whereas another leaf spring will make the ride harsher because it is active all the time.
That's all I know.
Edited by: mark5w