its cause its twin scroll. pots 1 and 4 are joined and pots 2 and 3 are joined, it removes the unbalanced turbulance to free power due to the gasses running smoother is prob the easiest way to discribe

alot of newer cars as twin scroll turbos aswell as alot of new design turbos such as the latest impreza

its a cool idea tbh,,,, though alot of extra work but should improve the spool time of turbos