Factory PSI Setting on Turbo?

From what I have heard the older Probe engines are not a very strong engine and wont take a lot of abuse. You can take it up with an internal wastegate but I wouldnt go more than a few psi if the engine is in good shape. On of the easiest ways to increase boost pressure is to get a manual boost controller. It is a simple device, is cheap and is very easy to install. Im not sure who makes these anymore. There is a downside to them though and that is that they tend to not be very stable with higher boost pressure. My suggestion would be to just leave boost where it is at. If he still craves boost tell him to look into seeing if the old SVO 2.3 turbo engine will fit in somehow.