"E" air valves

Who sells them?? ive looked all over and all i can find is SMC, Airlift, and GC. I just finished my suspension up with a SD.com 5gal 4 port tank running 4 250psi "E" 1/2" valves. I drove it to a show and around 65mph when i start to air out it has some wicked bad body roll. Im going to get a slim and skinny with more ports to run 8 valves so i need to find a place or someone to sell me 4more E valves.