I thought I posted this, but might be losing my mind.
So I sold the M6, picked up the M5 and now have slighty used (2 months) Hartge springs for the M6 Coupe.
So I will sell them, or if you want, buy me M5 springs from Hartge and we can swap.
I think Hartge is asking $750. PM me with best offer. They are springs they dont wear out, so if anything they are nice and settled in.