Never had a T4 but my mate had one on his, i was under the impression it's the kind of turbo that you can't just throw on any old engine - you need a proper spec'd engine that will work in partnership with the turbo to see the benefits.

I would say a cam change would be important along with pistons to suit, 83Ib injectors would be up to it but maybe an inlet change would benefit.

Best speak to an engine builder for advice as to what will and won't work