As a matter of fact diesels have far MORE engine-braking on the overrun
than gas engines, and are well-known for this. Adding a supercharger of
any kind to a diesel does not affect the engine-braking.

My own turbodiesel Corolla (and a bunch of other diesel cars I've
owned)attest to this.

As a 4-stroke gas engine is to a 2-stroke gas engine, so a 4-stroke diesel
is to a 4-stroke gas engine.

The Isuzu truck I rented recently had an exhaust brake; this was
sufficient to slow it a bit downhill, but not by much.