Split scroll, spools off of individual exhaust pulses instead of waiting for collector pressure to build.
Diesels have something like 30 or 40% less exhaust energy than a gas engine, and commonly have their pulses seperates so there are no overlapping cyls feeding split turbines. That's why so many diesels are 6 cyl/split bank (3 cyl banks with at most 120 degree cam duration so there is no overlap aka reversion between cyls in a bank). Look up Buchi, he had turbo theory worked out ten years before OEMs decided to like him and everyone though he was a loon. Also, fuck you.