Wasn't sure where to put this, so hopefully this will do. I have some NOS stuff that I bought a long time ago... probably 10 to 15 years ago. I have a complete ZEX kit, other than the jets... those I can't seem to find. I also have an extra 10lb bottle on top of the one that came with the kit. I used to use it on my old 1990 Integra. My question is, has this stuff changed over the years? Is this equipment likely to have any value to someone today? I've been told the bottles expire - where can I find the expiration date, and can they be affordably recertified? The bottles were barely used and are in excellent cosmetic condition. I'd love to get this stuff out of my garage, and if I could get some money out of it that would be even better.