2) Keep them in a box. When (if) you sell the bike, you can take off the Termi set and put it back to stock. As a rule, you'll never make your money back on mods if they go with the bike. You'll be better off selling them separately.
If you ever get a "fix-it" ticket for the exhaust you're running, you'll be upset you don't have the stockers sitting in a box somewhere.
Same applies if they decide to implement emissions regs for bikes. I would keep it.
Also
These 2 reasons are why I still have my stock 848 exhaust.