I don't know of any pre-built systems, but IMHO on a diesel, the fewer restrictions you have in the exhaust system, the better. You don't have to worry about burning valves or anything like that.
Essentially, if you went to a bigger size (all the way from the manifold) and eliminated the muffler altogether, you'd be okay. Just make sure that it's legal to straight-pipe the engine; many states don't allow it...in CA, though, all you need is some form of restriction, so it's okay to straight-pipe a turbo.
My $.02...good luck!