Didn't Cummins use several different size turbos on the 5.9 CTD?
I agree on not using just one designed for a small C.I. low RPM diesel motor on a car motor on gasoline with a lot less heat in the fuel to drive the turbos. work
It is probably way better to have more boost than you really need work scope

Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)