Remove header before selling?
 

I plan on selling my garage queen 13 FRS (32k with original brake pads). It currently has a SwainTech coated ACE A350 header with Delicious Tune. Does that really add much market value or would I be better off selling the header and reverting the tune back to stock? Its not that hard swapping the original manifold back in. I figure most Craigslist or Auto Trader buyers would rather have something without mods.

If you can find just the right buyer then they may pay you extra for it. Normally though it will add no value and you are better off just pulling it and selling it separately. On the other hand if you don't charge much for it still on the car it may make for a quicker sale as a "special feature". All depends on how much work you want to put in for a few hundred dollar really.

9/10 mods add no value.

You definitely will get more money back by selling aftermarket parts on the side.

No value. Take it off and sell. Many may be interested in header.

Taking it off should get more selling the used parts, but how much time and effort do you put in and how do you value your time and effort?

Like others have said, mods add no value.

Better to part out aftermarket parts and revert back to stock for resale.