Can someone here please help me post 2 graphs of hertz vs. rpm for a cone filter and the stock air box obtained from data logs? I got the 2 graphs pasted in word.

stock air box = the graph is pretty smooth
cone filter = the graph is so "saw-tooth"

This is real convincing evidence that the stock air box with stock paper filter allows the motor to pull as much air as a k&n cone w/o the fluctuation. Everytime there is a disturbance, the ecu will pull timing! My car feels much smoother going back from cone to the stock box/paper filter.

 

This has been seen many times on all the different engine management systems that retain the MAF.. This is also the reason that most of us (After trial and error) end up recommending the stock airbox with a good upgraded filter.

I posted some logs early on, but I lost my airbox a long time ago and don't have anything logged to directly compare with. But I can tell you from experience that tuning a car with a stock airbox, is much easier, a cone filter and intake pipe introduce anomolies that can sometimes be very difficult to tune around. Not because it alters the signal, but because depending on airflow, weather, and other conditions, the location and scale of this anomoly can change.

 

Also, the MAF is VERY sound and vibration sensitive, it has to be properly anchored and if it isnt, it will also be affected by it.. Many cone filter kits don't adequately anchor the MAF to prevent the bouncing and vibration. Also, some filter kits are affected by the Fan-wash from the electric fan, which can alter the MAF readings and even introduce some noise to the signal.