5sgte bogging/hesitating on accel. Options

[TurboToys]

My friend has a 94 celica gt that we turbo'd about 4 years ago. It had a st165 ct26 setup and map sensor, 7mge injectors, walbro 255 and no intercooler( i keep telling him to install one). The car ran beautifully until he decided to install a twin entry setup that he had layin around from his st185. I dont think this would be the cause but it quite possibly could be.

Going from a stop on accel. it bogs, spits, sputters, pops, hesitates as soon as the boost comes on according to the gauge. It kinda feels like boost leak on MAF sensor car. His narrowband A/F guage reads lean while this is happening then goes rich and takes off like a rocket.

Compression is at around 180psi on all cylinders, ignition timing is at 5 deg., swapped map sensors with the one from my st165, changed spark plugs, tried running it n/a and it still acts the same.

There are no codes in the ECM.

Just curious if anybody has experienced this or something similar.

Any help is greatly appreciated. Thanks