Air Filter Comparison
 

ProjectFarm released a nice informative video on air filters and as I expected not only do those K&N 'Performance' air filters deliver negligible results, they let a good amount more contaminants into the engine. If you're trying to shave .1 seconds off the acceleration time in a pristine environment, it might be worth it but if you actually daily the car it does not seem to be worth it at all. Just use a regular filter so that it can actually perform what it was installed to do, filter the bad stuff from getting into the engine.

Most of the "studies" only looks at the max flow and filteration rate, but conveniently ignore the ramping of airflow. If you plot the air volume versus time when throttle opens up, you will see K&N and foam filters ramp quicker than paper filters. That translates into better throttle response, so I would say it is not all bad or all good either way. More importantly is to understand the tradeoffs, and pick what you like most.

On a turbo car no air filter will give you any advantage as long as the car can meet the boost numbers it is programmed for. And stock the turbo is not under any strain for air so there is zero gain with even removing the air filter. Turbo cars in stock form no advantage to any air filter because the car is programmed to only make so much boost

RDX's are plagued with the "hesitation" from a start anyway as referenced by the massive thread "https://acurazine.com/forums/third-generation-rdx-2019-454/massive-hesitation-acceleration-after-braking-driving-me-nuts-979728/" on the general page. Adding a filter with higher "ramp up" time wouldn't do much because the car is inherently limited by the programming. I think a large part of the "better throttle response" you might feel would most likely be attributed to the placebo effect and yourself trying to justify spending the premium dollars on a filter that just filters less. You're trading effective filtration for subjective perceived "gains" which most likely is not there to begin with.

AZ4035 You are correct on the throttle lag. Manufacturer calls it torque on demand. But it is anything but. Hyundai, Acura, Kia, just to name a few all do it. If you hook up a scan tool to the vehicle and watch what happens its crazy. My wifes Santa Fe sport and I see Acura RDX do it. You will watch your throttle pedal percentage go up but nothing happens at the engine. Hyundai has a .6 to 1 sec delay before the engine does anything. With drive by wire they have screwed with the programming. Its way worse in the SUV for the same manufacturer than it is in the car of the same make with the same engine and transmission. They put it in the because these small 4 cylinder turbo can make peek torque as low as 1,600 rpm. So in a front wheel drive SUV it can be a lot easier to unload the inside front tire and get the wheel spinning. Taller heavier vehicle you can start to spin the tires. So I think for older folks or whoever they intended it for the vehicle will not let the engine come on at the same time with the pedal. I hate it.. Its bad between 5-20 mph. The Hyundai gets even worse if you are turning it senses the wheel and if you are turning on to a side street or a 90 degree turn its bad.