Variable Inlet Guide VaneS IŽd think. The Wiliams doesnŽt have them IIRC.
Sometimes its just a bleed air valve setting prob. I think the CJ bleed valve flow rates cant be changed manually, but if they differ from engine to engine youŽd see a split.
40-50° is alot and I would just not accept it from the mx shop.
We had a KingAir having HSI on both sides, which was a near perfect match afterwards. (before we had a 20-25° difference)
A few hours later it had a boroscope inspection that reavealed 2 missing stators on one side. One could positively see no real difference between the engines....