Waste of time if you expect more noise or airflow. I've had one on for a few years and makes no difference to sound.
The downside is they require maintenance and can if not correctly maintained allow more dirt in and hence wear.
I keep it purely as I use them on off road vehicles so servicing several at once is easy.
As Alan says the OEM airflow is already good, so steer clear of cones and all the downsides they can produce
