Or will resetting the ECU (detaching neg. battery cable) allow it to learn and compensate for the "extra" air?

Thanks.

One of them did, I remember seeing dyno numbers and someone looking at A/F ratio made the comment the HP increase may partially be due to the less rich condition. It was one that came out in the past few months, I think the Injen 3 (its the one you had to cut some small holes in the font side to get access), but it had a necked down portion just before the throttle body if I recall which was designed to aid in this I believe.

Someone did a good dyno side by side runs to confirm the +hp, so it seemed apples to apples, but I am not sure if the ECU would adjust for this, and cause the rich condition again and result in a drop closer to OEM intake. I am sure you can search for it, I think it was a G37'er post but there was talks about it on this board and linked to that one.

Resetting the ECU does nothing the ECU won't eventually do by itself... in fact, if you reset the ECU, it has to relearn everything rather than just what's been changed.