Most import cars are utilizing variable length runners. A vacuum operated solenoid controls a set of butterflies that change the path of incoming air. When vacuum is high, they seal off the short runners in favor of long runners that build torque. When vacuum drops under hard throttle, it shifts to a short runner path for higher upper rpm hp.
I'm a little suprised there haven't been any of those type manifolds out for the 5.0.
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