I have a Turbo'd D16Z6 with forged internals (rings/rods/ 8.5:1 pistions/seals etc) running 20psi but no head work done. I have a t3/t4 turbo (.63/.50 trim) and it starts to spool at 3k rpm and doesnt reach a peak boost til 4500k and when i shift at the boost cut of 20psi its usually at 6k rpm but it lets out most the power and it struggles to respool. I wanted to change turbo's and get a smaller turbo that spools faster and holds the same amount of boost, because the car doesnt actually pull as hard as it should on 20psi. What kind of turbo should i look into that possibly has a smaller housing then my current turbo, but still spools fast and hard, and gets mid-high range of power. I've been told a T3, a K04, a Gt28.. any ideas? Also i plan to have the head port and polished whihc should let through more exhaust gases and in turn help spool it faster.