The BMW N54 engine is one of the brand’s most iconic powerplants, known for its impressive tuning potential, strong internals, and smooth twin-turbo setup. Found in models like the 135i, 335i, 535i, and early Z4 35i, the N54 quickly became a favorite among tuners and enthusiasts. However, despite its durability and performance potential, the engine is not immune to wear and age-related...