I don't know if Lancarir has done any induction air testing, but  Van's A/C  has.  Although I was not prevelaged to the actual data, their induction "box" with alternate air and a K&N Filter gives equivalent Delta Pressure across the intake box with or without the K&N Filter installed. How can this be ?? WIthout  the filter, the air flow is relatively turbulent as it turns 90 Deg into the carb throat, the filter reduces this tendancy.  Their measurements were equivalent within the accuracy of the instruments themselves.. (pratically no difference)..