987 v 986 Air box

[edc]

I understand what you are saying and have similar thoughts. However, that car had 5 or 6 dyno runs on the same dyno with different mods over a period of time and the car in the configuration above was the only one to show lean running. Of course, that doesn't neccessarily mean its correct! Ironically, after the fitment of the 996 throttle body the AFR was back to 'normal'. You could interpret it as a spurious reading or that it indeed was running lean as the other 5 or 6 runs all seemed ok.