How to slow my dump and fill valve speed?

[charx2]

I have a problem here, I have 1/2 hoses run to all my valves and when I fill the bags it shoots the air into them and almost jumps the truck off the ground, same thing happens when I dump them valves only it slams it to the ground. It's very hard to dial into a certain psi for the bags because of how fast it fills and dumps and I have looked on ***************** and all those control valves are sold out. Is their a inexpensive way to slow the fill and dump? I would like it a little bit slower but not to slow ya know what I mean? Please, someone help me, I can't seem to figure out a solution and I would like to address it while I have the truck somewhat dissassebled. Thanks. I have 2 compressors, 2 5 gals, 8 valves and all 1/2 hoses and I'm not going to rerun all my plumbing. Also, would shocks slow it down?