G'day Nipper,
I've got an I6 ED Futura which is now about 50% EF (I'll get back to that) - as far as improving the ducting on the original ED setup, I had replaced the rubber duct which runs from the airbox to the throttle body with a rubber elbow, short section of aluminium pipe and couple of short lengths of silicon duct (rubber elbow and silicon duct 3 inch inside diameter and aluminium pipe 3 inch outside diameter with about 3mm wall thickness). The reason is that if you look inside the airbox end of the factory rubber duct you'll see it has a sort of ventury shaped restriction moulded into it! that means that although the throttle body inlet and airbox outlet are about 3 inch diameter, the duct is restricted to about 2.5 inches!!!
Another mod you could make is to fit an EF/EL type airbox (same as V8) - which will fit into the same place as your current airbox - and adapt it's inlet to be your outlet (fit ducting to the throttle body) then remove the rubber outlet adaptor in the lid and reverse the lid - which will make the outlet opening point at the passenger side front corner of the bonnet. Then if you trim away some of the rubber seal strip under the bonnet there, you should be getting a good supply of cool air.
I fitted a complete EF BBM Intake setup a couple of years ago. I got the complete thing from Ford Power in Perth for about $700. With other bits and pieces it all cost $900 once it was on. I had no trouble installing it - the trickiest part was swapping over the loom and even that really wasn't tricky as such - all the sensors etc are the same, just slightly different locations - ie. I just took the loom off the ED manifold and fitted it to the EF one.
Because I've had all sorts of trouble locating a BBM Solenoid Valve (the critter that operates the runner switching) it's still operating with the runners locked on long path. Even in just that configuration it improved performance noticeably - bottom and mid range better and top same as ED (that should improve once I have a solenoid and get the damned thing working as it should).
The BBM Solenoid should arrive any day now and then I've just got to organise an rpm switch to work it.
For other poor sods who are trying to find these, they live behind the windscreen washer bottle on EF and EL (don't know about AU).