$350 go get the "E" Vavles i know about 4 people that have them and they love them there rated at 450 psi the 1/2 and i think there only $35 a piece so times that by 8
I have the E 470's and will NEVER buy e valve agian the dumps stick and they wont even try to lift unless u have about 150psi in the tank, Get some GC 450's and you wont ever need to worry!
GC's and E air valves are almost identical. I hear that the new gc's don't have the problems that the old ones have.. but why risk it.. just run smc's or parkers and only have to buy them once.
Mike