I ran a TBE and Up-pipe without a tune for a few weeks. I found that:

a) It ran very rich
b) Fairly large boost kick, then not much else after that. So definitely not an optimised tune for the engine.

A tune levelled/smoothed it all out. Cleans up the tune and gets your economy back. You don't need to do other mods with a TBE other than the tune imho. Unless you are doing a new turbo, injectors, intercooler etc all at the same time to save doing 2 tunes later.