Maybe this is just an attitude I have, but when I see someone say "mods WORTH $15k" I walk away. The mods may have cost $15k but they are not worth anything near that. That single word tells me that the owner over-values his car and its really not worth inspecting as he will expect too much for it.

From my experience selling cars with mods, the mods may help clinch the sale but will not really impact on the sale price. I reckon you will stuggle to get any bites at $15k. If it were my car, I would change back some of the less painful mods to stock and sell them on here or Vortex, then advertise the car for $12k willing to negotiate to $11k.