Hey there, not trying to thread crap, but it's going to be a tough sale with so few posts/accredited sales on high dollar items like the exhaust and intakes. I recommend posting a few pictures of the items with something along the lines of a date on a post-it note to help convince potential buyers of your legitimacy.
There's a thread going on in the F10 5-series forums of a few members who were scammed out of thousands of dollars and i just want to save you and any potential buyers from a head-ache...
https://f10.5post.com/forums/showthread.php?t=1658025
Other than that, i wish you the best of luck with the sale of your items! It's hard to believe you were able to resist the urge to install all those wonderful mods!~