My AC lines that run behind the ABS aren't insulated.

Is it worth doing that, or has mine gone missing?

Seems silly to have a red hot engine bay, and freezing cold lines running through it.

 

Not insulated from factory. They are aluminum, so they reflect radiant heat. Don't really touch anything, so no conduction. Some convection, but the low side is the only one that is cold and it is going back to the compressor anyway (already done its job). Would improve efficiency a little, but the limiting factor on the AC in a d2 is not compressor capacity (unless we are talking one with rear AC).