stock airbox vs K&N rainshields???
 

Have been reading a lot about this conversion on early cars but I dont see discussion on real benefits or why to do it. Looking for your thoughts.

Cleans up the engine bay, makes cool intake noises.....

I believe there was a study done and they saw no additional gain. Stock is fine.

I used to be a real K&N fanboi years ago, however after reading various tests, not on airflow but on particle ingestion I steer clear of K&N's now.
They have some good applications such as race engines which will wear out rapidly no matter what air filter is used. However on road engines which are expected to have a long lifetime these days, they simply let too much small crud through, grinding your compression away..... Just my 0.02C

There have been many posts on this subject......K&N's VS Stock with and without spor mufflers.....etc. Basically when it came down to the numbers the stock airbox makes more HP.

I'm with Bart... K&N = Bad. Took out the MAF on my ML320 a few years back. Did a little research since then and found the stock paper elements work much better.