Unless any of you are willing to put some science behind this lower rpm / less throttle pressure "result", I think its safe to say that on modern vehicles with fuel injections there are a multitude of parameters that the ECU uses to set, adjust, and maintain the engine idle speed. Many things factor in, such as ambient air temperature, coolant temperature, O2 readings, engine load, knock sensor readings (octane), ignition timing adjustment, etc, etc. For someone to say "I did X and now the RPMs dropped at idle and while driving around town", that's not a very controlled experiment. What was the outside air temp that day? Before and after the swap? The humidity? How warm was the engine? Did that change before and after? Were you running the same grade fuel from the same pump at the same gas station? Is it winter blend fuel now? Was the A/C on? Defrost? Was the battery charging? Did you have the headlights on? Radio? Were you driving at the same rate? Location? Same gear position? Per the rules of math and the laws of physics, unless you were in a different gear or the transmission was slipping, there won't be a change in engine RPM at the same speed in the same gear as before, no matter what you do. You could add 1000HP to the motor, it doesn't change the drive ratio between the engine and the tires. That one's easy to debunk. The idle claim is more than likely just a difference in environment from the first recorded experience to the second. Not trying to discredit you OP or anyone else, but, at least in the limited context you've provided, there are some things that just don't add up, or are not possible (or plausible). Maybe you're not explaining it well? Or maybe you don't know how to explain what you're finding? My hunch is just that you're overstating / overly optimistic about the "results" you're seeing by changing the air filter element. Do you even have any CFM data to back up that one filter flows better than the other? Do you know for sure you're getting better flow? I guess the Mass Air Sensor readings could tell us that. Do you have recorded voltages from before and after?