I have an ARB CKMA12. I haven't used it much, but it did surprise me how fast it works. I never did time it though. I might have to go home today and see how fast it is and get back to you guys. It might not be the fastest one out there, but the selling factor for me was that they are very reliable and can take a beating, also that they are rebuild-able. I will never have to buy another one! If something ever goes wrong then I just buy replacement parts which are a lot cheaper than a new compressor. I used to have a cheap $50 unit for the XJ, but that quickly gave up. What a waist of money that was! I got this one from 4wd.com on sale with a discount. I got the compressor (ARBCKMA12), inflator w/pressure gauge (ARBARB605US), and tire inflation kit (ARB-171302) for about $250 shipped. I couldn't pass up that deal! I also just scored a 3 gallon pancake tank that will be mounted in the spare tire similar to what Russ did.