It is possible to run a "T" in the line from you boost signal to the wastegate actuator and leave the "T" open to the atmosphere. We did this on my friends 93 TSi FWD and it gave about 2.5 lbs. per "T". The boost increase depends on the gauge of the hose/"T".
Good luck and I hope you have the fuel to back up the boost.
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89 Mirage-Intake/Header/Exhaust
AIM-queerpuncher