Cool! you should check the Gamma II group on facebook (Im not on there), they sometimes come down this way.
It's basically replacing a stock turbo setup. Level of difficulty is around the same as changing a clutch.
It still retains good mpg, ability to pass emissions, and BNR will work with your tune if there are issues. I had a part throttle issue (overboost) and Jerry fixed me right up with a retune. I liked the overboost power lol, but it probs wasnt good for the turbo.
The gameplan was to add in the rear cat if need be to pass emissions, but it didn't need it, passed with no cats.
EDIT: Turns out the loss of power was adjustment of intake tube, cleaning MAF or IAT, or the old cam cover or PCV tube. Did all these things and the car ran well, actually better on the new tune BNR sent.