Interesting setup, do you have part no of bags used?
Regarding PSI, the firestone truck springs vs D2 bags are much larger diamater if they are 1t14c style bags, they cant really be compared, im not sure what i would be running in mine but it would be similar 40-60 depending on load but i run a longer bag, for the front in mine i would be closer to 80-100psi running a bag that is similar to a range rover/d2 setup.

