I run a 70mm 42R on my 2.0L car and see consistent 30psi by 6000rpm. On the street I have it setup for ~18psi and pump gas and it makes a little over 500 wheel. The car is a lot more laggy on pump gas and low boost. On big boost the car is a ****load more responsive, naturally. The biggest key factors IMO to making a bigger turbo responsive on these relatively smaller displacement engines is cam selection, cam timing and boost control.

Sometimes, after driving customers Evos with 60-67mm turbos I miss the responsiveness of the car but for the most part its hard to beat the fun of a 42R coming on hard at 6k and wrapping it out to 9800. The car picks up over 200whp in a little over 1000rpm span. That feels pretty nice lol