I have a K&N short ram intake on my 14 Challenger R/T. I also have a OBD2 bluetooth adapter that I use with the Torque app on my phone. I did a test of before the K&N and after, and the results were pretty close. On the highway, both air filters pulled air in that ranged from 2 to 5 degrees higher than the ambient air temperature. While sitting at a red light, or in traffic, the short ram did reach higher temperatures compared to the stock box. As far as airflow, you can tell the difference. The car pulls harder at higher rpms, where the stock box was restrictive. If living in areas where you have lots of traffic, I would actually get a cai that connects to the hole in the fender similar to a stock box. As far as HP gains manufacturer's claim, I think you might get that much of an improvement on a good day, with nice cool air, with the vehicle at proper running temp.

As far as the oil goes, I have heard people say that for years. I have used K&N filters since my first car, and I have put them in my parents vehicles also. As long as you oil the filter like you are supposed to, and let it dry a few hours before re-installing, you should have no issues. If you are heavy handed on the oil, you could have issues. Some people often think they know better than the directions...