Diamond Piston is in no way conected to Mahle. They do custom pistons in both billet and forged. I have used then in 6.7, 5.9 and destroked 6.7 ;s and in my extream destroked 4 inch cummins for the D motor. They will build you any bore , ring package any bowl design , and any compression height,
they also do custom pins in M300 and H13 tool steel
I have quite a few bowl designs on file for the 6.7 and destroked 6.7 in compression from 16 to 21 to 1