Really Good video on exhaust system myths ..... everything you'd like to know

I would think in the perfect world the crank would be designed, and the firing order would be designed for maximum scavenge and minimum restriction for the exhaust. Maybe thats where the cross bank headers comes in, but I could see problems working around accessories in and engine compartment. Talked to some ford engineers a a while back that designed an awesome motor only to find the engine compartment was configured incorrectly. 5 year setback.