But If I were replacing my turbos I would go with T28s. However you also should get your exhaust manifolds extruded, and intercoolers, twin air pop, and atleast 555 injectors (I would personally go with 720s and AFC).
And talk to DSP Racing for the T28s. And that should meet your goals if not exceed them. Then you can talk about how your Z is faster than your BPU Supra :-)