Turbo spool up times

when you say a bigger turbo such as an T3/T04b Hybrid Turbo takes longer to spool up than say a T3 Garrett Turbo. how much time/RPM are we talking about here to start boosting? I want the best turbo for my application for a GSR. I'm looking to not boost over 9 PSI EVER because I have no plans to build the motor in any way so for example the Revhard stage 2 sounds nice but would it increase spool up time by a lot compared to the non hybrid T3? I guess i'm afraid that the turbo will be too big and i'm going to be in lag more than I am in boost. Please give me some info on this.