[brucepick]

I've not seen any documented cases here of unwanted results due to air flow restriction, when driving for mpg with a fuel injected engine.

Running at 5000-8000 rpm at WOT or with a turbo added you probably would not realize full possible power without modding the intake. But if you're here, I suspect that's not how you're driving.

The amounts of fuel (and thus air) we are putting through our engines is less, if anything, than what the designers planned for, not more. Even unplanned added restrictions like a dirty filter has been tested to show near zero effect. The air flow sensor detects the net air going through the pipe and that's all the computer really needs to know.

Take a look at the "65 proven mods" thread sticky at the top of the EcoModding Central forum. You will find stuff on warm air intake and hot air intake (I'm pretty sure) but nothing on unrestricted intake or cold air intake. I use a WAI in winter.