As with Richard (StarCruiser) an intro would be nice.
I've had an ARB compressor fitted in the engine bay for 8 years now, runs faultlessly.
However, it's slow. Especially with bigger tyres. It's noisy too, but I think they all are.
Mine is a single, so the double that Chas has is probably.... well likely, twice as quick...
It doesn't bother me being slow, because I'm used to it and it gives me time for a cigarette while it's doing its business.
Somehow these days, everything has to be bigger and better, turbo, state of the art, LED, and eco-friendly.
The single ARB air pump is just that, and its reliable.
What more do you need? There's plenty of faster ones though, so you pay your money and get what you get. I rate them though, if that's what you wanted to know.