I fabbed those tanks up here in the shop with left over exhaust parts, a 3" off my civic and 4" from a cummins. There was some aluminum laying around as well, but a bit more difficult to weld so I opted for the stainless scrap bin. A long 3.5" pipe under the bumper support would have worked better volume wise, but the darn AC line is in the way - the price for keeping accessories.
A gauge is a great idea and plan to install one myself.
2nd tank is for a MAP sensing throttle feedback system I'm working on.
