was just wondering, if i take off the butterflies from inside the intake manifold is it a big difference power wise and petrol wise?

talk to FAST-XR.. he ported his out.. opening up the chamber... the same way as doing away with the butterflies.. (he cable tied them oopen).. he lost torque and bottom end power substantialy... did make a handul of kilowatts more at top end with the manifild porting.. but quickly resorted back to the standard manifold... was a dog for down low acceleration...

thats would be my answer ford freak as well

the manifold is a dual runner type allowing for iirc short runners at low rpm to improve low down torque and over 3500rpm i think they butterflies open for a longer intake runner length for high rmp torque

Ford Aus wouldn't have gone to all the trouble of designing and developing them, and then making them and adding to the price of the vehicle unelss they thought it was worthwhile.
And they're still used in the BF's. With the exception of the T's for obvious reason.