The other day I got to playing with the boost a little and totally blocked the waste gate closed.  The turbo would spike to 16psi which I am really impessed at since when I bought this turbo I never thought it would get past 10.  I would never run the turbo long with the waste gate totally blocked like that though.  First off I am still running a stock bottom end.. and second the turbine was probably spinning somewhere around 250,000 rpm like that.   I have since backed the boost down to a resonable 12 pounds.