There's way too many variables to answer your question as asked. The OEM ECU is set to keep the boost at the target of ~16 (15.6 is the stated boost) psi, but the OEM intercooler drops ~ 3psi, so the OEM K-04 turbo is blowing ~18-19psi to hit the OEM 16 psi target. The basic K-04 turbo is known to fail the seals and the turbine shaft if run at or above 15 psi for any period of time. Note there are quite a few documented cases of the OEM turbo causing exhaust smoke. There are causes for exhaust smoke other than the turbo, but the OEM turbo is a bit undersized for max power.
This all said, there are several of us running better intercoolers with essentially no pressure drop and up to 20psi for short bursts with the OEM turbo, no smoke or other problems at all. You will need a MBC/BCD or an aftermarket EMS to get more boost. The motor internals CAN hold 20psi IF you don't beat on it constantly. Some have had failures at much lower boost, even OEM, but the causes are far from established and remain questionable. YMMV
