I wrote:
> So, increasing the volume of air the intake tract can flow will have no
> affect on power or fuel economy (in a stock unmodified engine).
>
> If you drive your van at less than redline, increasing the size of the
> throttle body and/or increasing the size of the intake tract will have no
> affect
> on performance.  Certainly everyday city driving is far below redline,
> well
> within the capacity of the stock AFM and air filter.  Even if the stock
> system is
> restrictive, there should be lots of headroom for normal driving with a
> stock engine.

reply:
So I've done some research and have come to the conclusion that I was
incorrect in the above.
I learned a bit about air mass, volumetric efficiency and other factors.

For example, for the porsche 911 you can get a kit which replaces the bosch
flapper door afm
with a hot wire version.  A friend told me this seems to be a popular
conversion.
http://www.autothority.com/mass_flow.htm

You learn something every day.

Gary Lee