One exhaust pipe per bank of cylinders is the rule. There is no performance-based reason to split the exhuast flow of a single header into two pipes. It's a waste of stainless steel. Dual exhausts on Vee motors are beneficial because there are two headers. Splicing both headers into one exhaust pipe would create unnecesary back-pressure in the system, reducing performance. Therefore, each bank of cylinders gets its own.EuroZX3 said:how is it not functional? its just twin tipped exhaust. its not like the y pipe cuts off one of the tips from even flowing. its just not true dual. its twin tipped. not like its non functional hood scoop. 2 dif ball parks.