Just wondering. I saved my stock H to pass emissions, and it has been off the car for almost a year. My dad said they do, but I think he was just trying to make me worry.
I've also heard that.. perhaps that's in the scenario that it's left exposed to the elements. I would think if you plug the ends of the pipe it may preserve them a while longer, but then again, maybe that's what causes them to deteriorate over time.
i would suggest to run them for a little while before the immisions test. and make sure they are stored in a nice place out of the weather. doubt they go bad if not used