the arb twin puts out .5cfm more than the dual 400c. but at $600 is it worth the price difference? i have had mine in the bed of my truck for 5 years now. other than patching a leak on the air line one otr twice a year, they continue to still work.I wasn't sure what size tank I was going to run, but you think dual 400's would be better than the ARB Twin? I don't have a spare or bracket in the OEM location anymore, so there's tons of space to mount things back there.