Originally Posted by Silo

That's probably true but each factor (aftermarket part) counts and this creates and almost inifinite number of possible outcomes. Sam is running test pipes - this might have a totally diffferent effect in combination with his other mods, then say you running HFCs and a different intake.

We dont know if Sam's ECU has been rested before they did the "before" dyno run. Usually you would have expected the ECU to adapt better to the aftermarket parts and not run on a dangerously lean A/F. The only times I've seen this happen (on 350Z) is when the A/F meter housing diameter has been substantially increased without a tune.