Well considering they built the motor and ordered the wrong turbo kit and tried to custom fit it and installed it half ass. I think forged is responsible no matter about prior work done. The customer was trying to breck records and forged was well aware of this.
I will say this about the period of him leaving his car there. When the ordeal with Juan g37 happened it took over a year for him to get his car back. When your car is torn apart and no ther shop wants to take a car torn in pieces project sometimes you have no choice but to leave the car and hope for the best.