Storage is limited at my place. We do have emissions testing in washington but it's just the code reader. I've already passed (and am keeping my third cat) and my tuner will patch the CEL if I get one. I've never seen them do a sniffer test here in WA, or a visual inspection for that matter. My downpipe is catless because cheap. I really doubt I'll need it, I suppose I could always grab one from the junkyard or swap on the forums for a catted if need arises down the road.