Another thing I found is RB25DET's can be a lucky dip. My first motor with just Front Mount, Cat Back and Upped boost (around 10psi) pinged at anything over 4000rpm, and ALOT of pinging.
When you get the motor and ready to modify it be sure to run a good diagnostic check over it. Go to someone like Unique Autosports to do a major check and service first.