[pedelgax]

Hello all
This is my first BMW, in the past, I only had VAG cars
I bought this car with 8000km. Looking for more hp, I bought the JB+ one month ago. For the moment, it works fine, but, the first concern, is that I hear some knock under hard acceleration, always between 2500rpm and 3000rpm. The car feels better, but I do not like to hear this knocking in the engine. The knocking is not always, but when it happen, I see a black smoke
In order to discar problems, I remove the JB+, but the car continue with knocking, not as frecuently as with JB+ installed.
Has some one experimented the engine knocking issue in this engine?