I swapped out my OEM '13 XFR exhaust for the Mina Gallery exhaust within a few months of getting my car. I'm getting sick of the OEM exhaust taking up space in my closet. Is there any value to it, or is it basically just trash/scrap metal?

 

You should be able to sell it for a good price, Fleabay is your friend.
To an XFR owner who did the same as you but junked the OEM exhaust and now wants to go back to stock, possibly in preparation for sale.
Or to a V6 owner or Supercharged owner who wants the quad tips and exhaust valves of the XFR set up.
They command big money over in the UK where V6 diesel owners want to upgrade the stock exhausts.

 

Shipping is the big issue. If you can find someone within driveable distance you'll be fine. Otherwise, the shipping companies want more than $200 because the pipes are too long.

 

I just shipped a pair of "virtual" XFR exhausts (the custom set I had made up for the old XFR) from Adelaide to Brisbane, 2,112 km door to door, for $59.25 AU.
So that's around 1,318 miles for around $44 US.
That's just the rear pipes, mufflers & tips and I assumed that's what the OP was talking about, not the whole cat-back system.

 

If you want to sell just the tips, I would like to make a set of LOUD pipes for my ride.

I already cut the valves out but sometimes I would like more of a straight pipe sound.

Only takes an hour to drop out the rear boxes and swap in a set of straight pipes and it would be better if the tips were stock quad tips.