Detonation On My R33 Gtst. Please Help

[Black_R33Gtst]

I recently bought my R33 gtst and the original engine detonated and melted a piston. now replaced that engine with another rb25det and its still detonating under load. i was running 11psi boost but now its back to standard. only after market things on the car is cat back ehaust and bov. It cant exactly be the engine as it is a completely different engine and its having the same problem. the timing belt has been replaced and water pump. im not sure what it can be?

[MissR34]

may be the timing needs to be put back a bit.......??????????

octane booster is supposed to stop detonation aswell