onboard air system

I'm curious what you all think about this. I've spoken with plenty of folks who are happy with the ARB, even though it's considered expensive. I've used a cheap, twin portable compressor for a few years, and it seems faster, but I can tell it's on its last legs. It's time for me to install...

I am going to install an onboard air system. When I look at various wiring diagrams for installing relays on the internet, I get confused. (Apparently I must have understood them at sometime in the past, because I have some extra relays in my tool box !! ). There is a pressure switch in this...