Tigran
.Have you got guages showing pressure for each corner? These would show if you have a slight leak somewhere. I have my valves very close to the bags as per FD's description ,with 3/8" lines.The fr.n/s guage shows a drop in pressure after a time, which causes mine to lift unvenly on the front .I have to drop fully ,then lift to get it parrallel to the road .I can do this with about half filled tanks ,(which is just as well ,as I have to negotiate a large speed bump between my garage and the main road!)I have 2 x 5 gall tanks and 2 viair comps ,with scuba air back up . Just my 2p..............