K&Ns should have good airflow - just open cell foam. They definitely allowed carburetor cars to get more power, air - and dirt. Not going to affect how the transmission works in any car.
If the OP wants to test his beliefs: warm up the car, put the OEM filter on, test, take the filter out (no filter at all), test again. Other than an increase in noise, you won't detect a difference. The K&N will be in the middle of those two, also undetectable except for noise level.
2018 Kia LX HEV Metal Stream with Advanced Tech