how to solve cut outs at 4500 rpm

problem which no one in jamaica seems to know anything about.at about 4500 rpm on boost the car bucks and cut out.if i gradually make it climbs on boost it will be ok .can some one help me if they can.what can i do to get more fuel

What is your setup? How much boost? What are your fuel injectors rated? And your fuel pump? What ECU? etc...

firstly i am running evrything stock except the fuel pump iam running a bosch in line pump ,original pump went bad,the ecu is the factory digifant system.i am also running a fifth injector,i used a 16 v codl start injector but was told that digifant is low pressure high volume system so that fifth injector wouldnt work.i was considering using the 1.8 t fuel pressure regulator ,heard that its the same.anyway i pulled the cylinder head of the other day the bolts that hold the turbo to the exhaust broke and its seems find no detonation at all.if u have any ideas please let me know i really need to get car running properly now.only running 5 psi right now ,would like to run about 10 to 12 psi ultimately.