Fuel map should operate in "closed" loop mode so yes, if in fact it read rich when NOT at WOT - it would pull fuel...

At WOT - it does not rely on the sensors (as I understand it - open loop mode) - so it is strictly a function of the table values...

The assumption with LT's is that the sensor moves and the pressure would drop (PVNRT and all of that - and if not - why add them?) and potentially change the measurement...

Lacking specific data and what data I have read, my guess is that the difference is sufficiently small that it does not matter... (someone reported that brenspeed says he can see as much as 0.5 change in A/F based upon sensor position - so I am little surprised that he is saying no difference, but all of that is coming 5th hand through the internet BS filter)

Although it is "post combustion" - the A/F measurement can be influenced by the pressure and temp of the exaust - so if the tuners aren't seeing it, then presume it is sufficiently small to not matter...

 

Keep in mind that the O2 sensor is not moved very far with the longtubes added.

It is my understanding that the "front" pair of sensors are what are used for the fuel control and the "back" pair (post-cat) are merely there to check and see that the cats are working properly for "smog" reasons.

In any case, Cekim's point about the "internet BS filter" is a good one. Call your tuner and ask him what he thinks you should do. You might as well get it straight form the horse's mouth.