overboost

Hi everybody. Im new here, I live in japan so greetings to everybody. I just bought a soarer single turbo factory manual. It has over boost issue. Let me write down the mods so you guys know what it is. Mod List HKS front mount intercooler HKS air cleaner Aluminium Piping Aftermarket Blow off...

Hello guys I have a problem with my 1jz-gte vvti single turbo. I have decat and engine hits fuel cut in 3rd, 4th and 5th gear. I know a lot of people have same problem. Can you tell me which exhaust restrictor i need and where exactly i have to put them? Thanks!

as above pretty much standard car, has FMIC but standard turbo,actuator and boost solenoid but once you give it throttle it will overboost and hit fuel cut ive seen it hit 15psi by the time i had let off? have changed the actuator still no difference also while the actuator was off i checked...