Just wondering how much boost you think a s4 turbo can hold without having the potential of bad boost creep with a free-flowing exhaust, etc..

This is what I've done to it so far:

twin scroll removed

Turbine Inlet Ported

Internal Wastegate ported

I'm also thinkin about getting it sandblasted by a buddy to help with efficiency

 

I was creeping to 16 psi with a s5 turbo(wastegate ported, but stock flapper door), half bridge, and RB full exhaust.

With a good exhaust you can't control boost with the puny stock internal wastegate.