Hold up,just re read your description. High boost high rpm may not be pinking. Could easily be lazy tappet,piston slap,small end or anything mechanical really. Is it a light rattle or a loud deep kind,lol. If it is pinking its more likly to do it when you going up hill or whenever the engine is under high loads(low rpm,high gear,100% throttle). Although i really dont recommend driving whilst thr car is pinking you could try it by going along @30-40mph in 5th then nail it,if its going to pink it'll do it way before you get near scary revs,once the boost comes in it should start rattling its nuts off tbh.