S14 slant top Sputtering and breaking up in boost

[street_white180sx]

Hey guys i am a little bit stomped here. I have a S14 Zenki Silvia with a slant top motor. The problem i am having right now is when i am going in boost my car will sputter and fall flat at times or it will break up. Here is the checks that i have already made thus far.

Checks for Codes in the system only came up with code 55 which means no problem present. Changed plugs put sum ngk V powers in number 7 heat range. Found the fuel filter was dirty replaced the fuel filter and the problem is still present. Ohmed the ground side on the coil pack harness resistance is ok. Check fuel pressure at Idle 36psi ,when full throttle pressure jumps to about 50psi. Checked MAF voltage and voltage checked out OK. Checked TP checked out OK. Ohmed Ignition coils checked out ok. After all of these checks i am kinda stumped to what the problem is with my car.

What other Checks can i make or is there any suggestions to what my problem possibly could be.

Also Mods to Car are HKS air filter, HKS EVCIII, stock dp with 3 inch catback gutted cat runnin 0.8 bar and FMIC

Can it be dirty injectors or possibly anything else. Please this is my daily driver.