no you cannot.
You must run minimum wastegate actuator pressure.
eg. if the actuator is 6psi then you must run at least 6psi.
then to increase the boost on top of this you need a boost controller.
MBC or EBC respectively.
Ive built turbo 1.5s and 1.8s from the bottom up.
the 4g15s can get 500km a tank with occasionally heavy foot but otherwise normally driving.
4g93 have got best 450kms
These cars ran 10-12psi boost.
All in the tune.