I've posted in the past about larger WG flappers limiting boost capacity. It is a very real problem, one which I have measured and documented extensively on EVO16g sized turbos. If you plan to max the turbo out, you will blow the 34mm flapper open. I've also found that with the proper porting, there is no boost creep issue with that turbo on the stock sized flapper, so I have always recomended people run the stock flapper. This is assuming you're not trying to run 15 psi or something gay.
Looking quickly at your setup, there is no reason for you to be running less than 20 psi.