Well it could be a HKS, JAM or ToyTuning, more than likely a HKS or TT item. Take it you have a boost gauge? You will need to wind the actuator out a turn i.e make the arm longer to lower the boost a bit. My GT is doing this atm sometimes overboost's in 2nd and cuts but normally its just when giving it some in 3rd 4th and 5th, I just feather the throttle when I see the boost creeping up and try to avoid hitting cut. Then it seems to go into limp mode if you hit cut and feels sluggish high rpm but still shows alot of boost on the gauge, when it does this I just disconnect the battery and start it again and its fine. As said if you want to run a FCD you will need to get a different FPR and get them both set up on the rollers otherwise BOOM. Hope this helps