I've always heard that the readings aren't as accurate if taken from the Tail pipe. Seeing as the exhaust goes through a muffler and Cat if installed. Now would it matter for his setup? More than likely no.
i have seen many 500 600 and 700whp cars dyno'd with tail pipe WB its only roughly 100-200 rpms if that delayed on reading. and maybe .1-.2 AFR leaner. but usually its whatever your tuner is comfortable with.
The G Spot Hero
"Nitrous is like a hot girl with STDS, you know you want to hit it but your afraid of the consequences."