I will be running it as is with the standard Vanagon TD exhaust at first but will fit an EGT from day one. I plan to have a straight 2.5 inch pipe made up, probably from the BAE exhaust I have now, but that depends on the turbo I choose and what manifold goes with it. If it is too loud then a single muffler will be added. (There are no emissions checks for a diesel where I live.)
From reading on this forum the general consensus seems to be that a smaller turbo will spool up faster and be better for low rpm power but that I will lose out at higher rpm. For my purposes that sounds like a reasonable compromise but I will need to drive the beast post-transplant to be sure where/if improvement is needed. A VNT sound amazing but I really don't have the time needed to play with setting one up.
I will be fitting an EGT and probably a boost gauge to give me a reasonable idea of what the engine is doing.
As I said, I don't need a high rpm hot rod but I do ideally want to get around 90-100hp and 150 lbs/ft (or more) of torque.