I am looking for 1 Mahle Piston assembly, ( I have 7 ), managed to misplace one while shifting.
So I am trying to identify what pistons that I have and where I can buy 1 from, the markings on the Piston are
11RF 0300 32511 50_033 T7
any help is appreciated

Call them direct, I did that with my old s2000 back in the day when no one was making forged pistons for the f20c. Mine were made by Ross Pistons and a 1 off set. After my cylinder 2 valves decided to punch a hold in the piston, I called them up and they had all the specs on file with the S/N on the pistons. Was able to get a replacement.