I have a 08 GL 450 ride was becoming harsh and noisy so i decided to replace the airmatic compressor & valve block because the compressor was very noisy, i also replaced the air filter put it all together and it was all fine except the ride quality was the same, very hard & bumpy, i have no leaks in system and no warnings on dash, truck is always nice and high no sagging, so i decided to replace rear shocks struts only but that didnt change anything either, now before i go and replace front struts also, i wanted to know if my car has some kind of dampening system that is not working properly, it doesnt have the adaptive dampening system (ads) just the normal airmatic with the rise & lower button, does anyone know what the problem can be of such a hard ride and getting worse? My next step would be to replace front struts if there is nothing else related to the dampening of the truck,, please HELP