i ran the airlift bags for a long time -they are what came on my 4runner when i bought it, then over time they developed a leak that got worse and worse... anyhow i ended up replacing them with the firestone bags, not that i have anything bad to say about the airlift bags, but i wanted to try something else to see how they worked and how long they lasted (i dont know how long the airlift bags lasted as they were in the rig when i bought it). one thing i like about the firestone bags is they are designed to fill the whole coil, no spacer puck is used. so for me with my lift, i used the old spacer puck from the airlift kit with the new firestone kit, and it came out perfect.
that spacer puck in the airlift kit is designed to run with a stock rig, no lift, the bags are very small and limited, if you are gonna use an air bag kit on a lifted rig even with a slight lift i recommend using the firestone bags. maybe call airlift and see if they will sell just the spacer puck, and use that like i did. thats what im gonna try and do with my GX when i lift it. if you deflate the bags completely they do not affect articulation or flex.